A U.S. income tax form used by taxpayers to report their realized capital gains or losses. Investors are required to report their capital gains (and losses) from the sales of assets, which result in different cash values being received for them than what was originally paid, in order to affix some amount of taxation to the income and wealth that is generated through investment activities.

Schedule D is a complicated form that has confounded investors for years. However, changes in legislation came into effect with the Jobs And Growth Tax Relief Reconciliation Act of 2003, which made qualifying dividends subject to capital gains tax instead of normal income tax, the form and its applicable regulations have become moderately less complex.