"...Some people have to pay federal income taxes on their Social Security benefits. This usually happens only if you have other substantial income (such as wages, self-employment, interest, dividends and other taxable income that must be reported on your tax return) in addition to your benefits.
No one pays federal income tax on more than 85 percent of his or her Social Security benefits based on Internal Revenue Service (IRS) rules..."
Read more at ssa.gov
