Chapter 12 Income Taxes

Marginal and Average Tax Rates

From the perspective of macroeconomics, this complexity is daunting, particularly when we remember that the details of the tax system vary from country to country and year to year. The income tax is evidently not a simple thing that can be incorporated in a straightforward way into our frameworks. We cannot hope to incorporate all these features of the tax code into our theory without getting completely bogged down in the details. If we are going to make sense of how taxes affect consumption behavior, we must leave out most of these complicating elements. The challenge for economists is to decide which features of the tax system are critical for our analysis and which are peripheral and can be safely ignored.

One noteworthy feature of the income tax system is that not everyone pays the same amount of tax. Table 12.1 "Revised 2010 Tax Rate Schedules" shows the income tax schedule for the year 2010 for a single taxpayer.There are other schedules for members of a household filing jointly. These and related tables are available from “Forms and Publications,” Internal Revenue Service, accessed September 20, 2011, http://www.irs.gov/formspubs/index.html. It indicates how much tax a must be paid for a given level of taxable income.

To use this table, you must first find your taxable income. Suppose it is $20,000. Your tax is then determined from the second row of the table. You would owe 837.50 + 0.15 × (20,000 − 8,375), which is $2,581.25.

Figure 12.3 shows the relationship between taxes and income implicit in the tax schedule summarized in Table 12.1 "Revised 2010 Tax Rate Schedules". This figure shows the amount of tax you must pay given your adjusted gross income (upper panel) and your taxable income (lower panel). We see two key facts:

1. As an individual’s income increases, he or she pays more in tax (the line slopes upward).
2. As an individual’s income increases, he or she pays a larger fraction of additional income in tax (the line becomes steeper at higher levels of income).

This leads us to two ways to think about the tax schedule a household faces.

Figure 12.3

The figure shows the amount of tax owed by a single individual in the United States who takes the “standard deduction.” The upper panel has adjusted gross income on the horizontal axis, whereas the lower panel has taxable income on the horizontal axis.

As shown in Table 12.1 "Revised 2010 Tax Rate Schedules", there were six different tax rates in effect in 2010, ranging from 10 percent for low-income individuals to 35 percent for high-income individuals. The tax rates in the fourth column are the marginal tax ratesThe tax rate paid on additional income. since they represent the tax rate paid on marginal (that is, additional) income. Thus higher income households pay higher marginal tax rates. The marginal tax rate can be seen graphically as the slope of the line in Figure 12.3.

We are often interested in knowing what fraction of an individual’s income goes to taxes. This is called the average tax rateThe ratio of total taxes paid to income.. Returning to the example we calculated earlier, if you have an income of $20,000 and thus pay taxes of $2,581.25, your average tax rate is equal to 2,581.2520,000=0.129, or 12.9 percent. The marginal tax rate of 15 percent is greater than the average tax rate of 12.9 percent. There is a difference between the tax you pay on average and the tax rate charged on the last dollar of income.The average tax rate can also be given a graphical interpretation. It is the slope of a line from the origin to the point on the graph.

Leaving aside the details of exemptions and deductions, the essence of the income tax code is captured in the table and figures we have just presented. Even these, however, are quite complicated. We want to build income taxes into our framework of the economy, so it would be nice if we could decide on a simpler way to represent the tax code. The art of economics lies in deciding how to take something complicated, like the US income tax code, and represent it in as simple a way as possible while still retaining the features that matter to the problem under discussion.

Looking at Figure 12.3, we can see that the relationship between taxes paid and taxable income looks approximately like a straight line. It is not exactly a straight line because it becomes steeper as marginal tax rates increase. For our purposes in this chapter, however, it is a reasonable simplification to represent this relationship as a line—that is, to suppose that the marginal tax rate is constant.

In addition, we ignore the standard deduction and exemption. That is, we suppose that people start paying taxes on their very first dollar of income. Thus we suppose that

Representing the tax schedule this way is fine if we want to examine the economy as a whole and are not particularly concerned with the way in which taxes affect different households. We use this simplified model of the tax system at various times in this chapter.

Effects of Changes in Tax Rates

We can use this simple model of the tax system to see how a change in the income tax rate affects both individuals and the economy as a whole. Suppose there is a cut in the tax rate. Since taxes paid = tax rate × income, the immediate impact is to reduce the amount of taxes households pay: for a given income, a reduction in the tax rate reduces taxes paid. This means that disposable incomeIncome after taxes are paid to the government., which is the income left over after paying taxes and receiving transfers, increases.

What do households do with the increase in disposable income? A likely answer is that a typical household spends some of this extra income and saves the remainder. If all households follow this pattern, then the increased spending by each household translates into larger consumption in the aggregate economy. At this point, the power of the circular flow of income will take over, and the level of income and output in the economy will increase even further.

As the economy expands, the amount of taxes paid starts to increase. In other words, one consequence of a tax cut is that the tax base (income) expands. The ultimate effect of a tax cut on the overall amount of taxes paid depends on both this expansion of the tax base (income) and the reduction of the tax rate.

Taxes and Income Distribution

The effects of a tax cut are not the same for everyone. Changes in the tax code affect the distribution of income. If we want to understand such effects, however, it is a mistake to use our simple model of the tax system. We must instead examine how marginal tax rates are different at different levels of income. Suppose that marginal tax rates increase with income, which means that average tax rates increase with income. Higher income households then pay a larger fraction of their income as taxes to the government. As a result, the distribution of income after taxes is more equal than the distribution of income before taxes.

Imagine that we take two individuals with different levels of income and calculate their tax payments and after-tax income. Suppose that the first individual earns $20,000 per year and the other earns $200,000. Table 12.2 "The Redistributive Effects of Taxation (in US$)" shows the amount of tax each pays and their income after taxes, based on the tax schedule from Table 12.1 "Revised 2010 Tax Rate Schedules". Notice from the table that the marginal tax of the high-income household is 33 percent, compared with the 15 percent marginal tax of the low-income household. The total tax paid by the high-income individual is $51,116.75, which is almost 20 times the tax paid by the low-income household. Whereas the pre-tax income of the richer household was 10 times greater than that of the poorer household, its after-tax income is 8.5 times greater.

This example shows that the tax code redistributes income from high-income to low-income households. What is more, the redistribution does not necessarily stop here. We have not said anything about what the government does with the tax revenues it receives. If the government transfers all those revenues to low-income households, then the combined redistributive effect of taxes and transfers is even stronger.

When we talk about the effects of taxes on labor supply and disposable income, keep in mind that the size of these effects is different for households at different levels of income. These varying effects matter for the politics of tax cuts because lawmakers pay close attention to which income groups are affected by tax policy.

The Scenario

In his inaugural presidential address, President Kennedy famously said, “My fellow Americans, ask not what your country can do for you; ask what you can do for your country.” The Kennedy administration recruited top individuals in all fields (“the best and the brightest”) to come to Washington in this new spirit of commitment to public service.See David Halberstam, The Best and the Brightest (New York: Ballantine Books, 1972).

Every president has a group of economists, known as the Council of Economic Advisors (CEA; http://www.whitehouse.gov/cea), that provides advice on economics and economic policy. The list of members and staff of the 1961 CEA reads today like a “who’s who” of economics. James Tobin and Robert Solow were prominent members of the economics team; both went on to win Nobel Prizes in Economics. The chairman of the CEA was Walter Heller, an economist known for a wide variety of contributions on the conduct of macroeconomic policy.

The economists in the Kennedy administration observed that there had been three recessions in the two Eisenhower administrations (1952–1960): one from 1953 to 1954 after the Korean War, one from 1957 to 1958, and one in 1960. You can see these in Figure 12.4 "Real GDP in the 1950s". The CEA members and staff thought that more aggressive fiscal and monetary policies could be used to keep the economy more stable and prevent such recessions. Their goal of moderating fluctuations in the economy was based on the framework of the basic aggregate expenditure model, which had been developed in the aftermath of the Great Depression, augmented by some developments in economic thinking from the 1940s and 1950s. Based on that analysis, they believed that fiscal and monetary policies could be used to control aggregate spending and hence real GDP.

Figure 12.4 Real GDP in the 1950s

The chart shows real GDP in the United States between 1952 and 1960, measured in billions of year 2000 dollars.

Source: Bureau of Economic Analysis.

This group of economists had, on one hand, a clearly defined goal of stabilizing the macroeconomy and, on the other hand, a set of policy instruments—economic variables such as taxes, government spending, and interest rates—that were under the control of policymakers. They also had a framework of analysis (the aggregate expenditure model) that explained how these instruments could be used to achieve their goals. Finally, they had a president who was willing to listen and take their advice. Never before had economists had such tools and wielded such influence.

The opportunity to test their ideas arose toward the middle of the Kennedy presidency. In the middle of 1962, it was apparent to the Kennedy administration economists that the economy was beginning to sputter. The growth rate of real GDP was 7.1 percent in 1959 but decreased to 2.5 percent and 2.3 percent in 1960 and 1961, respectively.Economic Report of the President (Washington, DC: GPO, 2005):table B-2, GPO Access, accessed September 20, 2011, http://www.gpoaccess.gov/eop/2005/2005_erp.pdf. Their response was to initiate a tax cut.

As is usually the case when a major fiscal policy action is under consideration, there was a lengthy time lag between the initiation of the policy and its implementation. Even though the tax cut was proposed in 1962, President Kennedy never saw it put into effect. He was assassinated in November 1963; the tax cut for individual households and corporations was not enacted until early 1964. For households, tax withholding rates decreased from 18 percent to 14 percent, leading to an estimated tax reduction of about $6.7 billion. Taxes on corporations were also decreased; the reduction in taxes for 1964 was expected to be about $1.7 billion. By 1965, the economists expected that taxes would be lower by $11 billion. In 1965, nominal GDP was about $719 billion, so these changes were about 1.5 percent of nominal GDP.

For many observers of the macroeconomy, this was a watershed event. The Economic Report of the President proclaimed 1965 the “Year of the Tax Cut.” In retrospect, these years were the heyday of Keynesian macroeconomics: for the first time, the government was using tax policy in an attempt to fine-tune the economy.

Figure 12.5 "Tax Policy during the Kennedy Administration" shows what happened to average and marginal tax rates. Marginal tax rates were very high at the time—much greater than in the present day. At high levels of income, more than 90 cents of every additional dollar had to be paid to the government in taxes. Consequently, average tax rates were also high: an individual with taxable income of $100,000 (a very high level of income back then) had to pay about two thirds of that amount to the government. The Kennedy tax cuts reduced these tax rates. Even after the tax cut, the marginal and average tax rates both increased with income. In other words, the tax system still redistributed income across households. But when we compare 1963 and 1964, we see that the marginal tax rate did not increase as rapidly under the new tax policy. Therefore, this channel of redistribution was weaker under the new tax policy.

Figure 12.5 Tax Policy during the Kennedy Administration

The charts show the impact of the Kennedy tax cut. Part (a) highlights how the marginal tax rates for households changed from 1963 to 1964, and part (b) shows the impact on average tax rates.

Source: Department of the Treasury, IRS 1987, “Tax Rates and Tables for Prior Years” Rev 9-87

For their policy to be successful, Kennedy’s advisors had to ask and then answer a series of questions. How big a tax cut should they recommend? How long should it last? What would be the effect on government revenues? What would be the effect on real GDP and consumption? Economists working in government today confront exactly the same questions when contemplating changes in tax policy. Questions such as these epitomize economics and economists at work.

Looking back at this experiment with almost half a century of hindsight, we can ask additional questions. How well did these policies work in terms of achieving their goal of economic stabilization? What actually happened to consumption and output? Was the tax policy successful?

The Kennedy economists needed a quantitative model of economic behavior: a formalization of the links between their policy tools (tax rates) and the outcomes that they cared about, such as consumption and output. Using the aggregate expenditure model, they wanted to know how big a change in real GDP they could expect from a given change in the tax rate. To use the model to study income taxes, we need to add some theory about how spending responds to changes in taxes. Accordingly, we study the effects of income taxes on household consumption and then discuss how changes in consumption lead to changes in output.

Although we are using a historical episode to help us understand the effect of taxes on the economy, this chapter is not intended as a lesson in economic history. Variations of this same model are still used today to analyze current economic policies. Indeed, in response to the economic crisis of 2008, many countries around the world cut taxes in an attempt to stimulate their economies. By studying the experience of the early 1960s, we gain insight into a critical part of macroeconomics: the linkage between consumption and output.

Having said that, economics has advanced significantly since the 1960s, and the state-of-the-art analysis for that time seems oversimplified today. Modern economists think that the policy advisers in the 1960s neglected some key aspects of the economy. Their insights were not wrong, but they were incomplete. Our understanding of the economy has evolved since Tobin, Solow, and Heller designed the nation’s tax policy.

Household Consumption

We begin by studying the relationship between consumption and income. We first develop some ideas about how households make consumption decisions, and, on the basis of those ideas, we make some predictions about what we expect to happen when there is a cut in taxes. We then examine the evidence from the Kennedy tax cut.

The Consumption Function

One way to represent consumption smoothing is by means of a consumption functionA relationship between current disposable income and current consumption.. This is an equation that relates current consumption to current disposable income. It allows us to go from an abstract idea about consumption behavior—consumption smoothing—to a specific formulation of consumption that we can use in a model of the aggregate economy.

We suppose the consumption function can be represented by the following equation:

consumption = autonomous consumption + marginal propensity to consume × disposable income.

• We make three assumptions:

  1. Autonomous consumption is positive. Households consume something even if their income is zero. If the household has accumulated a lot of wealth in the past or if the household expects its future income to be larger, autonomous consumption will be larger. It captures both the past and the future.
  2. We assume that the marginal propensity to consume is positive. The marginal propensity to consume captures the present; it tells us how changes in current income lead to changes in current consumption. Consumption increases as current income increases; the larger the marginal propensity to consume, the more sensitive current spending is to current disposable income. By contrast, the smaller the marginal propensity to consume, the stronger is the consumption-smoothing effect.
  3. We also assume that the marginal propensity to consume is less than one. This says that not all additional income is consumed. When the household receives more income, it consumes some and saves some. The marginal propensity to save is the amount of additional income that is saved; it equals (1 – marginal propensity to consume).

Table 12.3 "Consumption, Income, and Saving" contains an example of a consumption function where autonomous consumption equals 10,000 and the marginal propensity to consumeThe amount by which consumption increases when disposable income increases by a dollar. equals 0.8. If the household earns no income at all (disposable income = $0), it still spends $10,000 on consumption. In this case, savings equal −$10,000. This means the household is either drawing on existing wealth (accumulated savings from the past) or borrowing against income expected in the future. The marginal propensity to consume tells us how the household divides additional income between consumption and saving. In our example, the household spends 80 percent of any additional income and saves 20 percent.

Table 12.3 Consumption, Income, and Saving

Disposable Income ($)	Consumption ($)	Saving ($)
0	10,000	−10,000
10,000	18,000	−8,000
20,000	26,000	−6,000
30,000	34,000	−4,000
40,000	42,000	−2,000
50,000	50,000	0
60,000	58,000	2,000
70,000	66,000	4,000
80,000	74,000	6,000
90,000	82,000	8,000
100,000	90,000	10,000

For example, when income is equal to $20,000, consumption can be calculated as follows:

consumption = $10,000 + 0.8 × $20,000 = $10,000 + 0.8 × $20,000 = $26,000.

The household is still dissaving but now only by $6,000. Table 12.3 "Consumption, Income, and Saving" also shows that when income equals $50,000, consumption and income are equal, so savings are exactly zero. At income levels above $50,000, the household has positive savings.

Figure 12.6 "Consumption, Saving, and Income" shows the relationship between consumption and income graphically. We also graph the savings function in Figure 12.6 "Consumption, Saving, and Income". The savings function has a negative intercept because when income is zero, the household will dissave. The savings function has a positive slope because the marginal propensity to saveThe amount by which saving increases when disposable income increases by a dollar. is positive.

Figure 12.6 Consumption, Saving, and Income

The graph shows the relationship between consumption and disposable income, where autonomous consumption is $10,000 and the marginal propensity to consume is 0.8. When disposable income is below $50,000, savings are negative, whereas at income levels above $50,000, savings are positive.

As well as the marginal propensity to consume and the marginal propensity to save, we can examine the average propensity to consumeThe ratio of consumption to disposable income., which measures how much income goes to consumption on average. It is calculated as follows:

average propensity to consume =consumptiondisposable income.

When disposable income increases, consumption increases but by a smaller amount. This means that when disposable income increases, people consume a smaller fraction of their income: the average propensity to consume decreases.In terms of mathematics, we are saying that, if we divide through the consumption function by disposable income, we getconsumptiondisposable income=autonomous consumptiondisposable income+marginal propensity to consume.An increase in disposable income reduces the first term and the average propensity to consume. Meanwhile, the ratio of saving to disposable income is called the savings rateThe ratio of household savings to disposable income.. For example,

savings rate =savingsdisposable income.

The savings rate and the average propensity to consume together sum to 1. In other words, a decline in the average propensity to consume equivalently means that households are saving a larger fraction of their income.

Because the consumption and savings relationships are two sides of the same coin, economists wishing to find the actual values of autonomous consumption and the marginal propensity to consume can examine data on consumption, savings, or both. If the data were perfect, we would get the same answer either way. For the United States, both consumption and savings data are readily available, but in some countries the data on savings may be of higher quality than the consumption data, in which case economists use savings data to understand consumption behavior.

The Effects of a Change in Income Taxes

We can now figure out the effects of a cut in taxes on consumption and saving. A reduction in taxes will increase disposable income. From the consumption function, this results in an increase in consumption equal to the marginal propensity to consume times the increase in disposable income. The average propensity to consume decreases. To summarize, if taxes are cut in the economy, we expect to see the following:

• An increase in disposable income
• An increase in consumption that is smaller than the increase in disposable income (that is, a marginal propensity to consume less than 1)
• A decline in the average propensity to consume

When natural scientists such as molecular biologists or particle physicists want to see how good their theories are, they conduct experiments. Economists and other social scientists have much less ability to carry out experiments—certainly at the level of the macroeconomy. The Kennedy tax cut, however, is like a “natural” experiment in that there was a major policy change that we can think of as a change in an exogenous variableA variable determined outside the model that is not explained in the analysis.. It is not, in truth, completely exogenous. We already explained that the tax cut was enacted in response to the poor performance of the economy. We are not badly misled by thinking of it as an exogenous event, however. We can therefore use it to see how well our theory performs. Specifically, we can look to see whether disposable income and consumption do behave as we have predicted.

Empirical Evidence on Consumption

Before we turn to those specific questions, let us examine some data on consumption. Figure 12.7 "Consumption and Income" shows the behavior of consumption and disposable income from 1962 to 2010. The measures of both income and consumption are in year 2005 dollars. This means that the nominal (money) levels of income and consumption for each of the years have been corrected for inflation, so that we can see how the real level of consumption relates to the real level of income.

Figure 12.7 Consumption and Income

The charts show consumption and personal disposable income (in billions of year 2005 dollars) from 1962 to 2010. Consumption and disposable income grew substantially over this time (a) and there is a close relationship between consumption and income (b).

Source: Economic Report of the President (Washington, DC: GPO, 2011), table B-31, accessed September 20, 2011, http://www.gpoaccess.gov/eop/tables11.html.

Toolkit: Section 16.5 "Correcting for Inflation"

You can review how to correct for inflation in the toolkit.

The first thing we see in Figure 12.7 "Consumption and Income" is that both consumption and disposable income grew substantially over the 1962–2010 period. This should come as no surprise. We know that the US economy grew over this period, so we would expect that disposable income and consumption would also grow. Figure 12.7 "Consumption and Income" reveals that, as a consequence, there is a close relationship between consumption and income, and consumption expenditures are, on average, about 91 percent of disposable income. Although Figure 12.7 "Consumption and Income" looks something like a consumption function, we should not take this relationship as strong evidence for our theory because it is primarily caused by the fact that both variables grew over time.

Aggregate Income, Aggregate Consumption, and Aggregate Saving

The 1964 tax cut was not designed to influence consumption in isolation but rather to have an impact on the overall economy via its effect on consumption. So far, we have argued that a change in taxes leads to a change in disposable income and hence a change in consumption. Now we complete the story, noting that a change in consumption will itself affect the level of real GDP and hence have further effects on the level of disposable income.

In the case of the Kennedy tax cut of 1964, the economists advising the administration at that time had a fairly specific idea of how changes in consumption would affect the overall economy. They argued that the $10 billion tax cut would lead to an increase in GDP of about $20 billion each year. How did they create this estimate? To answer this question, we need to embed our theory of consumption in the aggregate expenditure model.

We motivated our consumption function by thinking about the behavior of an individual household. We now presume that our household is in some sense average, or representative of the entire economy, so the consumption relationship holds at an economy-wide level. Different households might actually have different consumption functions, but when we add them together, we still expect to find an aggregate relationship similar to the one we have described.

The economists of the time used a framework that was closely based on the aggregate expenditure model. When prices are sticky, the level of GDP is determined in that model by the condition that planned spending and actual spending are equal. The model tells us that the level of real GDP depends on the level of autonomous spending and the multiplier,

where the multiplier is calculated as (11−marginal propensity to spend). Given the level of autonomous spending in the economy and given a value for the marginal propensity to spend, we can calculate the equilibrium level of real GDP.

The marginal propensity to spend is not the same thing as the marginal propensity to consume, although they are connected. The marginal propensity to spend tells us how much total spending changes when GDP changes. Total spending includes not only consumption but also investment, government purchases, and net exports, so if any of these are responsive to changes in GDP, then the marginal propensity to spend is affected. Likewise, autonomous spending is not the same as autonomous consumption. Autonomous spending is the sum of autonomous consumption, autonomous investment, autonomous government purchases, and autonomous net exports. Finally, the marginal propensity to consume measures how consumption responds to changes in disposable income, not GDP.

In our analysis here, we continue to focus on consumption and suppose that the other components of spending—government spending, investment, and net exports—are exogenous. That is, these variables are all unaffected by changes in income and so are all included in autonomous spending. In addition, we presume that the amount that the government spends is not affected by the amount that it receives in tax revenue.

To find out the effects on the economy of a change in income taxes, we take the equation for real GDP and write it in terms of changes:

This equation tells us we need two pieces of information to work out the effect of a tax change:

1. The marginal propensity to spend because this allows us to calculate the multiplier
2. The effect of a tax change on autonomous spending

Let us think about the marginal propensity to spend first. We want to know the answer to the following question: if GDP changes by some amount (say, $100), what will happen to spending? There are three pieces to the answer.

1. A change in GDP leads to a change in personal income. Remember from the circular flow of income that GDP measures production, income, and expenditure in the economy. Firms receive income when they sell their products. Most of that income finds its way into the hands of households in the form of wage and salary payments or dividend payments. Firms hold onto some of the income that they generate, however, to replace worn-out capital goods and finance new investments. In the early 1960s, personal income was about 78 percent of GDP. So if GDP increased by $100, we would expect personal income to increase by about $78.
2. A change in personal income leads in turn to a change in disposable income. As we explained at length, personal income is taxed, so disposable income is less than personal income. Since we are considering the effects of a change in taxes, we need an estimate of the marginal tax rate facing consumers. We know from Figure 12.3 that this varied across individuals, but researchers have estimated that, for the economy as a whole, the marginal tax rate in 1964 was about 22 percent.Robert J. Barro and Chaipat Sasakahu provide estimates of the “average marginal tax rate.” Barro and Sasakahu, “Measuring the Average Marginal Tax Rate from the Individual Income Tax” (NBER Working Paper No. 1060 [Reprint No. r0487], June 1984), http://www.nber.org/papers/w1060. To put it another way, households would keep about 78 percent (= 100 percent – 22 percent) of their personal income. So if personal income increased by $78, disposable income would increase by about $61 (= 0.78 × $78). (It is a meaningless coincidence that these two numbers are both 78 percent.)
3. Finally, a change in disposable income leads to a change in consumption. According to the 1964 Economic Report of the President, the CEA thought that the marginal propensity to consume was about 0.93. So if disposable income increased by $61, we would expect consumption to increase by about $57 (= 0.93 × $61).

Putting these three together, therefore, we see that an increase in GDP of $100 causes consumption to increase by $57. The marginal propensity to spend in this economy was equal to about 57 percent. It follows that the CEA thought that the multiplier was equal to about 2.3 because

Now let us think about the change in autonomous spending. We have said that taxes were cut by about $10 billion. We expect that most of this tax cut ended up in the hands of consumers. Based on the marginal propensity to consume of 0.93, we would therefore expect there to be an increase of about $9.3 billion in autonomous consumption,

Putting these two results together, we find that our prediction for the change in GDP as a result of the tax cut is

Our answer is not exactly equal to the $20 billion predicted by the CEA, but it is very close. As you might expect, the CEA was working with a more complicated model than the one we have explained here, and, as a result, they came up with a slightly smaller number for the multiplier.

A Word of Warning

All our analysis so far has ignored the fact that, through the price adjustment equation, increased real GDP causes the price level to rise. This increase in prices serves to choke off some of the effects of the increase in spending. In effect, we have ignored the supply side of the economy. It is not that the Kennedy-Johnson administration economists were naïve about the supply side, but they thought the demand side movements were much more relevant for short-run policymaking purposes. More recent economic experience has convinced economists that we ignore the supply side of the economy at our peril. Modern macroeconomists would be careful to augment this story with a discussion of price adjustment.

Tax Cuts and Private Saving

We have already conducted most of the analysis we need to examine the effects of tax cuts on saving. We know that a tax cut increases disposable income. Our theory of consumption smoothing tells us that households will respond by increasing consumption and savings. Specifically, we predict that a dollar’s worth of tax cuts will cause saving to increase by (1 − marginal propensity to consume).

It is tempting to conclude that tax cuts therefore will lead both to higher consumption, increasing output now, and to higher saving, increasing output in the future. Such an argument is not right because it looks only at saving by households. We also need to look at the effect of the tax cut on the government surplus or deficit.

Tax Cuts and National Saving

If the government is spending more than it receives in tax revenues, then it is running a deficit. Conversely, if it is spending less than it receives in tax revenues, it is running a surplus. National savings is the combined savings of the government and the private sector. If the government is running a deficit,

and if the government is running a surplus,

These are just two different ways of saying the same thing because, by definition, the government surplus equals minus the government deficit.

What happens if the government cuts taxes? If there are no associated changes in government spending, then tax cuts translate dollar for dollar into the government budget. One million dollars worth of tax cuts will increase the deficit (or decrease the surplus) by exactly $1 million. So even though a tax cut of a dollar increases private savings by $(1 − marginal propensity to consume), it costs the government $1. The net effect (to begin with) is to reduce national savings by an amount equal to the marginal propensity to consume.

If the tax cut succeeds in increasing income, there is additional savings resulting from the multiplier process. Still, we expect the overall effect is a decrease in national savings. For example, consider the Kennedy tax cut again. Taxes were cut by $10 billion. The resulting change in income was roughly $20 billion. With the marginal propensity to save equal to 0.07, the offsetting increase in private savings would have been about $1.4 billion. Evidently, the result was a large decrease in national savings.

Here we see one of the biggest problems with tax cuts. They are attractive in the short run because they stimulate aggregate demand and increase output. They are also attractive politically, for obvious reasons. Unfortunately, they have the adverse long-run consequence of reducing national savings. When national savings decreases, the economy does not build up its capital stock so quickly, so future living standards are lower than they would otherwise be.

Labor Supply

Each individual faces a time constraint: there are only 24 hours in the day, which must be divided between working hours and leisure hours. An individual’s time budget constraintThe restriction that the sum of the time you spend on all your different activities must be exactly 24 hours each day. says that, on a daily basis,

The labor supply decision is equivalently the decision about how much leisure time to enjoy. This decision is based on the trade-off between enjoying leisure and working to purchase consumption goods. People like having leisure time, and they prefer more leisure to less. Leisure can be thought of as a “good,” just like chocolate or blue jeans or cans of Coca-Cola. People sacrifice leisure, working instead, because the money they earn allows them to purchase goods and services.

To see this, we first rewrite the time budget constraint in money terms. The value of an hour of time is given by the nominal wage. Multiplying through the time budget constraint by the nominal wage gives us a budget constraint in dollars rather than hours:

The second term on the left-hand side is “nominal wage income” since that is equal to the number of hours worked times the hourly wage.

Because wage income is used to buy consumption goods, we replace it by total nominal spending on consumption, which equals the price level times the quantity of consumption goods purchased:

This is the budget constraint faced by an individual choosing between consuming leisure and consumption. Think of it as follows: it is as if the individual first sells all her labor at the going wage, yielding the income on the right-hand side. With this income, she then “buys” leisure and consumption goods. The price of an hour of leisure is just the wage rate, and the price of a unit of consumption goods is the price level. Finally, if we divide this equation through by the price level, we see that it is the real wageThe nominal wage corrected for inflation. (the wage divided by the price level) that appears in the budget constraint:

It is the real wage, not the nominal wage, that matters for the labor supply decision.

Changes in the Real Wage

What happens if there is an increase in the real wage? There are two effects:

1. There is a substitution effectAs the real wage increases, households substitute away from leisure toward consumption of goods and service and thus supply more labor.. An increase in the real wage means that leisure has become relatively more expensive. You have to give up more consumption goods to get an hour of leisure time. If leisure becomes more expensive, we would expect the household to “buy” fewer hours of leisure and more consumption goods—that is, to substitute from leisure to consumption. This effect predicts that the quantity of labor supplied will increase.
2. There is an income effectAs income increases, households choose to consume more of everything, including leisure.. An increase in the real wage makes the individual richer—remember that we can think of income as equaling 24 × the real wage. In response to higher income, we expect to see the household increase its consumption of goods and services and also increase its consumption of leisure. This effect predicts that the quantity of labor supplied will decrease.

Putting these predictions together, we must conclude that we do not know what will happen to the quantity of labor supplied when the real wage increases. On the one hand, higher real wages make it attractive to work more since you can get more goods and services for each hour of time that you give up (the substitution effect). On the other hand, you can get the same amount of consumption goods with less effort, which makes it attractive to work less (the income effect). If the substitution effect is stronger, the labor supply curve has the standard shape: it slopes upward, as in Figure 12.10 "Labor Supply".

Figure 12.10 Labor Supply

The response of the quantity of labor supplied to the real wage depends on both an income effect and a substitution effect. When the substitution effect is larger than the income effect, the supply curve has the “normal” upward-sloping shape.

In the end, the shape of the labor supply curve is an empirical question; we can answer it only by going to the data. And as you might be able to guess, it turns out to be a difficult question to answer, once we start dealing with the complexities of different kinds of labor. The view of most economists who have studied labor supply is that higher real wages do lead to a greater quantity of labor supplied, but the effect is not very strong. The income effect almost cancels out the substitution effect. This means that the labor supply curve slopes upward but is quite steep.

The Effect of the Reagan Tax Cuts on the Supply of Labor

Suppose an individual knows the nominal wage but also knows that she is going to be taxed on any income that she earns at the going income tax rate. The wage rate that matters for her decision is the after-tax real wage. Her real disposable income is

All our discussion of labor supply continues to hold in this case, except that we need to replace the real wage with the after-tax real wage since it is the after-tax wage that matters to the individual.

Figure 12.11 "Labor Supply Response to Tax Cut" shows the effect of a cut in taxes. If the labor supply curve slopes upward, the tax cut leads to an increase in the quantity of labor supplied. And if labor supply increases, then potential output also increases. In other words, one effect of tax cuts is to induce people to work harder and produce more real GDP. To keep things simple, Figure 12.11 "Labor Supply Response to Tax Cut" is drawn supposing that there is no change in the equilibrium real wage as a result of the tax cut. In fact, we would expect the real wage to decrease somewhat as well. Buyers of labor as well as sellers of labor would benefit from the tax cut. Indeed, it is this decrease in the real wage that induces firms to purchase the extra labor that individuals wish to supply. (If we included this in our picture, then the after-tax real wage would still increase but by less than shown in the figure.)

Figure 12.11 Labor Supply Response to Tax Cut

The wage that matters for labor supply decisions is the after-tax real wage. If income taxes are cut, and the real wage is unchanged, then households will supply more labor.

The Laffer Curve

Supply-side economics was controversial and generated a great deal of debate back in the 1980s and since. Yet the argument that we have just presented is not really controversial at all. Almost all economists agreed that as a matter of theory, cuts in taxes could lead to increases in the quantity of labor supplied. The disagreements concerned the magnitude of the effect.

Some proponents of supply-side economics made a much stronger claim. They said that the positive effects on labor supply could be so large that total tax revenues would increase, not decrease. They argued that even though the government would get less tax revenue on each dollar earned, people would work so much harder and generate so much more taxable income that the government would end up with more revenue than before.

This argument was encapsulated in the so-called Laffer curve. Economist Arthur Laffer asked what would happen if you graphed tax revenues as a function of the tax rate. Obviously (he observed) if the tax rate is zero, then tax revenues must be zero. And, Laffer argued, if the tax rate were 100 percent, so the government took every penny you earned, then no one would have an incentive to work at all, and the quantity of labor supplied would drop down to zero. Once again, income tax revenues would be zero. In between, tax revenues are positive.

Figure 12.12 "Laffer Curve" shows an example of a Laffer curve. There is some tax rate that will lead to the maximum possible revenue for the government. This itself is not that interesting: the goal of the government is not to raise as much tax revenue as possible. But if the tax rate lies to the right of that point, then—as the picture shows—a cut in taxes will increase tax revenues.

Figure 12.12 Laffer Curve

The Laffer curve says that it is possible for a reduction in the tax rate to lead to an increase in tax revenues. Although this is a theoretical possibility at very high tax rates, most economists view the Laffer curve as a theoretical curiosity with limited applicability to real economies.

Just as almost all economists agreed that there would be some supply-side effects of income tax cuts, almost all economists agreed that the Laffer curve argument was inapplicable to the US economy (or indeed any other economy). The evidence indicated that the effects of tax cuts on hours worked were likely to be relatively small. Almost no economists actually believed that the economy was on the wrong side of the Laffer curve, where tax cuts could pay for themselves.

Unfortunately, the Laffer curve argument was politically appealing, even though it was not supported by economic evidence. Buoyed by this argument, President Reagan oversaw both tax cuts and big increases in government spending. As a result, the US government ran large budget deficits. Following on from the ERTA, President Reagan and President George H. W. Bush after him were both forced to increase taxes to bring the budget back under control.The economic history of the United States in the 1980s was quite complex. Because this chapter concerns income taxes, we have considered only one of the policy changes of the Reagan administration. Other changes in tax policy were designed to promote savings. We have not discussed other aspects of President Reagan’s fiscal policy (there were large increases in government purchases), the tight monetary policy pursued by the Federal Reserve, or the behavior of interest rates and exchange rates. All these are matters for other chapters.