Politics & Policy

Before You File . . .

. . . do a little extra math.

People working on their tax returns would do well to spend a couple of minutes doing a little extra math before finishing their calculations. The following is important information that may surprise many taxpayers and could affect routine decisions made about investments and lifestyles.

A first additional calculation is to simply find your mean, or average, tax rate. This is the tax you owe on line 62 of the 1040 form divided by the income figure on line 22. (To be more accurate, you should also add in income for tax-exempt bonds, which can be found on line 8b.)

Many people delude themselves into thinking that they aren’t actually paying any taxes if they end up with a refund. But a refund just means that you had too much money withheld from your paycheck. You need to be aware of the amount you really paid: withholding less any refund or plus the check you had to write to the Internal Revenue Service.

A more important tax number takes a little effort to calculate. It’s what is called the marginal tax rate, which is the tax you paid on the last taxable dollar you earned. This number will probably be well higher than your average tax rate. To find the marginal rate, take your taxable income from line 42 and see where you fall in the following table, which shows marginal tax rates for married couples filing jointly.

Table 1

Taxable Income

Marginal Tax Rate

$0 – 14,300


14,301 – 58,100


58,301 – 117,250


117,251 – 178,650


178,651 – 319,100


Over 319,100


The marginal tax rate is critical for knowing the after-tax rate of return on different types of investments. For example, the spread between taxable bonds and tax-exempt bonds has lately been about 19 percent. Thus, if you are in the 10 percent or 15 percent marginal tax bracket, you should not buy municipal bonds. You would be better off buying taxable bonds. Those in higher brackets should do the reverse.

According to the Tax Policy Center, the vast bulk of taxpayers either pay no federal income taxes at all or are in the 10 percent or 15 percent marginal tax brackets. However, growing numbers of taxpayers are finding that something called the alternative minimum tax is raising their marginal rate.

The AMT is a completely separate tax system with two brackets, 26 percent and 28 percent, which apply to a broader definition of taxable income than is calculated on the regular tax form. In particular, taxpayers lose several deductions, such as that for state and local taxes. This tends to force people living in high-tax states, like New York and California, to pay higher taxes under the AMT. Taxpayers must pay the AMT if it is higher than their regular income tax. Table 2 shows the distribution of marginal tax brackets, including the AMT, among tax filers in 2004.

Table 2

Marginal Rate

Percent of Total









26 (AMT)


28 (Regular)


28 (AMT)






Various types of business investments are also taxed differently because of provisions in the tax code. Those that are debt-financed bear a lower tax burden than those that are equity-financed due to the deductibility of interest, even with the lower tax rates on dividends and capital gains that now exist. For this same reason, when taxpayers invest in housing the return is taxed much more lightly than if they were to invest in stocks or a business.

According to new calculations by the Treasury Department, the marginal effective tax rate on equity-financed investments is close to 40 percent, but there is actually a negative tax rate on those that are debt-financed. Tax rates also vary considerably depending on whether an investment is in land, buildings, inventories, or equipment, and on whether a business is organized as a “C” corporation, “S” corporation, partnership, or sole proprietorship.

The Treasury Department has also calculated that the 2001-2003 tax cuts sharply lowered the effective marginal tax rate on all new investments. The tax rate in the corporate sector has fallen from 33 percent to 27.9 percent, and from 20.6 percent to 17.5 percent for non-corporate businesses. Overall, the tax rate on new investment has fallen from 17.2 percent to 14.2 percent. In time, this will raise the amount of investment in the economy, which will increase productivity, economic growth, and, ultimately, wages and living standards.

We may not like thinking about the taxes we pay or our tax rates, but they are important economically. At least once a year we should take the time to become aware of them. It’s important information that can help us make both financial and political decisions.

– Bruce Bartlett is senior fellow for the National Center for Policy Analysis. Write to him here.


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