Up to 85 percent of Social Security benefits are subject to income tax as of 2015, depending on an individual's combined income, reports the Social Security Administration. Those for whom Social Security is the only source of income probably owe no taxes on Social Security benefits, states the IRS.
As of 2015, individuals with combined incomes of less than $25,000 or couples filing jointly with combined incomes of less than $32,000 owe no income taxes on Social Security benefits, according to the Social Security Administration. Individuals who make between $25,000 to $34,000 and couples who make $32,000 to $44,000 are taxed on up to 50 percent of their Social Security benefits, while those who earn over these limits are taxed on up to 85 percent of their benefits. Combined income is calculated by adding adjusted gross income, half of Social Security benefits and tax-exempt interest.
About 50 percent of those who received Social Security benefits in 2014 paid some income tax on their benefits, as reported by the Congressional Budget Office. Higher-income taxpayers incur larger tax bills not only because they pay taxes on a higher percentage of Social Security benefits, but also because they are in higher tax brackets. In total, under 30 percent of Social Security payments in 2014 incurred taxation.