You are credited only with earnings for which you pay Social Security (also known as FICA) taxes. If you are an employee, you can find this information on your W-2. If you are self-employed, the amount is taken from the Schedule SE you file as part of your 1040 personal income tax return.

Earnings from interest, dividends, and other sources (generally referred to as unearned income) are not included. Regardless of your total earnings for a year, Social Security counts only earnings that are subject to FICA tax. The contribution and benefit base is $97,500 for wages paid and self-employment income earned beginning in 2007. In other words, regardless of your wages or self-employment earnings for 2007, only the first $97,500 is taxed and only that amount is used in computing a benefit. However, there is no limit on the amount of income that is taxed for Medicare.