Why are capital gains taxed at a lower rate than normal income?
There are many reasons, which other answers have already discussed. I want to emphasize and elaborate on just one of the reasons, which is that it avoids double taxation, especially on corporate earnings.  Generally, for corporations, its earnings are already taxed at around 40% (for the US - including State income taxes). When dividends are distributed out, it is taxed again at the individual level. The effect is the same when equity is sold and the distribution is captured as a capital gain. (I believe this is why the dividend and capital gain rates are the same in the US.) For a simplistic example, say there is a C Corporation with a single owner. The company earns $1,000,000 before income taxes. It pays 400,000 in taxes, and has retained earnings of $600,000. To get the money out, the owner can either distribute a dividend to herself, or sell her stake to another person. Either choice leads to $600,000 getting taxed at another 20%~30% or so at the individual level (depending on the State). If we calculate the effective rate, it is above 50%! Many people invest in stock, including mutual funds, and the dividends and capital gains are taxed at lower rates. Individual tax returns that contain no wage income often have very low average tax rates for this reason. However, the investments themselves are continuously paying out their own taxes, or accruing taxes in the form of future tax liability.