It appears that capital gains are treated differently than other forms of income. What are the differences in how capital gains are earned compared to other forms of income? How does the tax code treat capital gains? What can I do to take advantage of these differences without being a wealthy investor?
I think this question is very nearly off-topic for this site, but I also believe that a basic understanding of the why the tax structure is what it is can help someone new to investing to understand their actual tax liability. The attempt at an answer I provide below is from a Canadian & US context, but should be similar to how this is viewed elsewhere in the world.
First note that capital gains today are much more fluid in concept than even 100 years ago. When the personal income tax was first introduced [to pay for WWI], a capital gain was viewed as a very deliberate action; the permanent sale of property. Capital gains were not taxed at all initially [in Canada until 1971], under the view that income taxes would have been paid on income-earning assets all along [through interest, dividends, and rent], and therefore taxing capital gains would be a form of 'double-taxation'. This active, permanent sale was also viewed as an action that an investor would need to work for. Therefore it was seen as foolish to prevent investors from taking positive economic action [redistributing their capital in the most effective way], simply to avoid the tax.
However today, because of favourable taxation on capital gains, many financial products attempt to package and sell capital gains to investors. For example, many Canadian mutual funds buy and sell investments to earn capital gains, and distribute those capital gains to the owners of the mutual fund. This is no longer an active action taken by the investor, it is simply a function of passive investing. The line between what is a dividend and what is a capital gain has been blurred by these and similar advanced financial products. To the casual investor, there is no practical difference between receiving dividends or capital gain distributions, except for the tax impact.
The notional gain realized on the sale of property includes inflation. Consider a rental property bought in 1930 for $100,000, and sold in 1960 for $180,000, assuming inflation between 1930 and 1960 was 70%. In 1960 dollars, the property was effectively bought for 170k. This means the true gain after accounting for inflation is only $10k. But, the notional gain is $80k, meaning a tax on that capital gain would be almost entirely a tax on inflation. This is viewed by many as being unfair, as it does not actually represent true income. I will pause to note that any tax on any investment at all, taxes inflation; interest, for example, is taxed in full even though it can be almost entirely inflationary, depending on economic conditions.
A tax on capital gains may restrict market liquidity. A key difference between capital gains and interest/rent/dividends, is that other forms of investment income are taxed annually. If you hold a bond, you get taxed on interest from that bond. You cannot gain value from a bond, deferring tax until the date it matures [at least in Canada, you are deemed to accrue bond interest annually, even if it is a 0 coupon bond].
However, what if interest rates have gone down, increasing the value of your bond, and you want to sell it to invest in a business? You may choose not to do this, to avoid tax on that capital gain. If it were taxed as much as regular income, you might be even more inclined to never sell any asset until you absolutely have to, thus restricting the flow of capital in the market. I will pause here again, to note that laws could be enacted to minimize capital gains tax, as long as the money is reinvested immediately, thus reducing this impact.
Political inertia / lobbying from key interests has a significant impact on the tax structure for investments. The fact remains that the capital gains tax is most significantly an impact on those with accrued wealth. It would take significant public support to increase capital gain tax rates, for any political party to enact such laws. When you get right down to it, tax laws are complex, and hard to push in the public eye. The general public barely understands that their effective tax rate is far lower than their top marginal tax rate. Any tax increases at all are often viewed negatively, even by those who would never personally pay any of that tax due to lack of investment income. Therefore such changes are typically made quietly, and with some level of bi-partisan support. If you feel the capital gains tax rules are illogical, just add it to the pile of such tax laws that exist today.
Were capital gains taxes not lower, companies would have an incentive to minimize the portion of the value they create that materializes as capital gains. They would do this by using more debt financing (since interest is deductible) than equity financing. This would have a destabilizing effect on the economy.
Low capital gains taxes help encourage investment over spending. This is believed to improve economic growth.
Given these factors, it is generally believed that the current capital gains tax rate is very close to the optimal rate. That is, a higher tax rate would not result in greater tax revenue.
Bluntly, a higher income tax rate on earned income does not really discourage people from working harder and earning more money. But a higher rate on capital gains does discourage investment. Essentially, it's because investment is more discretionary.
Here are three key factors that you do not explicitly state:
- Capital gains are a result of the appreciation of investment value when it is sold. Dividends are cash payments and are not taxed at the long-term capital gains rate for many people (for many they are not taxed at all, and for those in the 40% tax bracket they are taxed at a higher rate).
- Short-term (from investments held less than 1 year) capital gains are taxed as ordinary income
- Long-term capital gains are taxed at 15%, which is lower than the marginal tax rate of about 23% of taxpayers (according to this chart)
So while I cannot say exactly why the tax law is the way it is, I can infer that it encourages long-term investments rather than short-term, which would seem to be a good thing for society overall. The fast that capital gains are taxed at all somewhat discourages cashing out investments (although I suspect it's more of a nuisance factor - the cash received is likely more of an incentive that the tax is a disincentive).
To me, the lower tax rate for capital gains is largely due to governments encouraging economic activity.
Note that investments usually come from your normal income, which is already taxed. Capital gains tax is essentially punishing people who take the extra effort to put their money into work. If the tax rate is high, it would definitely cause people to rethink about investing, thus slowing the general economy down.
Every economy wants growth and for growth to come you need investments. So, you must provide some motive for people to risk their money (every investment has inherently a degree of risk or if you want uncertainty about the outcome). As a result the tax on capital gains is lower than on other types of income (because the risk is almost zero). The tax is considered in the calculation of the net interest rate. And you can see this as the interest which the investors demand in order to invest their money.
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.