Although Social Security retirement benefits alone are generally not taxable, people with even a modest amount of income in addition to their Social Security payments may pay taxes on their benefits. If you file a federal tax return as an individual and your "combined income" -- calculated by adding one-half of your Social Security benefit to other income, including nontaxable interest income -- is between $25,000 and $34,000, up to 50 percent of your benefits may be considered taxable. If your combined income is above $34,000, up to 85 percent of your benefits may be subject to income tax. If you file a joint return and you and your spouse have a combined income between $32,000 and $44,000, you may have to pay tax on up to 50 percent of your benefits. If your combined income is more than $44,000, up to 85 percent of your benefits may be subject to income tax.
For more information on the taxation of Social Security retirement benefits, visit the Social Security Administration’s “Income Taxes and Your Social Security Benefits” page, or call the Internal Revenue Service's toll-free telephone number, 1-800-829-3676, and ask for Publication 554, Tax Guide for Seniors, and Publication 915, Social Security Benefits and Equivalent Railroad Retirement Benefits. You can also access these publications on the IRS Web site (http://www.irs.gov). Calculating the taxes you owe on your Social Security retirement benefits is also explained in the instruction booklet accompanying your Form 1040 federal tax return.