Corporate Income Taxes
Buffett fails to mention that the corporations who issued the stock he's talking about face an income tax of their own. Most public companies, if they're making more than $18.3 million per year, pay 35%. This is also the rate for the top individual tax bracket.
So think about a dividend. The income that a corporation makes is first taxed at 35%. Then, a dividend is paid out -- after taxes. If you obtain that dividend, should it be taxed? Well, it already was -- at 35%. For this reason, it makes sense to tax it at 0%. If you tax it more, then you are taxing the income it produced twice.
The retained earnings (after-tax income not paid out to dividends) that a firm makes contribute to its growth, which should cause its stock price to rise. So if you sell the stock, you'll have a gain on sale. Like the dividend income, this gain has already been taxed at 35%. So again, it makes sense to tax the capital gain at 0%.
Taxation of Gains on Payroll Income
But that's not all. Let's think about the mechanics of investing. Let's say you want to invest in the Disney Company, because you like think its stock will perform well in the future. You have some savings, which you accumulated by spending less money than you earned in your job over the past few years.
That money you invest has already been taxed, since it came from your income. So if Disney's stock does well and you sell it for a gain in five years, should you be taxed on that return? Remember, the money you invested already got hit with a tax when you first earned it. Like before, it makes sense for the capital gains tax to be zero here. Why should you be penalized for investing that money instead of spending it?
Where Buffett's Argument Begins to Make Sense
This doesn't mean that there's nothing to Buffett's argument. It could make sense to tax investors at a higher rate in two situations.
Professional Investors
If a professional investor manages to earn money by investing for her clients, then her earnings should be taxed at the regular payroll tax rate. That is to say, if the income that someone collects by investing isn't derived from his capital he directly invests, then he should be taxed like any other worker. To the extent that investors manage to escape regular payroll tax rates by collecting capital gains by investing other people's money, reform should be sought.
But professional investors also often invest some of their own money along with their clients' money. That any income derived from capital that they put in themselves should be taxed just like the capital gains of non-professional investors.
Short-Term Gains
In the examples above, we were imagining that the investor held the stock for several years, as the corporation's income was taxed each year. As a result, the profit on capital gains should not also be taxed. But what if an investor holds the stock for only days, hours, or even minutes? Now it could make sense to tax the gain. In this case, the investment is speculation, which shouldn't receive the same benefit as investing that contributes to a firms' long-term capital position. Indeed, such short-term capital gains aren't really subject to the corporate income in the same way as long-term gains.