Capital Gains Tax & Losses
If you realize a profit when you sell an asset, such as a stock, you have a capital gain. In other words, if you sell an asset for more than you bought it for, you made a profit and will need to pay capital gains tax. (see IRS Topic 409)
The IRS differentiates between long-term capital gains (on assets held for over one year before selling) and short-term capital gains (sold within one year or less). The tax rate for long-term capital gains is lower than short-term. You may be required to make estimated payments, if you have substantial capital gains.
If you have capital losses (the sale price is lower than what you paid originally), you can claim no more than $3,000 per year (married filing jointly). You may be able to carry the loss forward to later years if your total loss is over $3,000.