Social Security benefits are not necessarily a free tax-ride.That's coming up next on Tax Break. --break-- UNDATED (AP) _ How do you know if you owe federal income tax on your Social Security benefits? Generally, if the benefits represent your only income, then they are not taxable, and you probably don't have to file a federal income tax return. The answer, however, becomes more complicated if you received other income during the year. To do the calculations, use the worksheet worksheet found in the instruction book provided with the Form 10-40 or the 10-40-A. If your retirement benefits are subject to tax, you might able to avoid the problem in future years by having the government withhold federal income tax from your benefits. Complete Form W-Four-V (W4V), Voluntary Withholding Request, and file it with the Social Security Administration. Copyright 2005 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.