Figuring out what you owe can be complicated, here is some information to understand what is taxable under Social Security.
Social Security is taxable at three different levels, based upon how much other income you have and your income tax filing status.
First, your Provisional Income. This is 50% of your household Social Security benefits plus all of your other taxable income, plus any tax-free income.
Next, there are two breakpoints in the taxation - if your filing status is Married Filing Jointly, the breakpoints are $32,000 and $44,000. If your filing status is Single or Head of Household the breakpoints are $25,000 and $34,000. These breakpoints are the same if your filing status is Married Filing Separately and the couple does not live together during the tax year. If your filing status is Married Filing Separately and the couple lives together, there are no breakpoints; in this case your Social Security is always 85% taxable.
How to do the calculation? If your Provisional Income (defined above) is less than the first breakpoint based on your filing status, then none of your Social Security is taxable.
If your Provisional Income is greater than the second breakpoint, the amount above the second breakpoint is 85% taxable. This amount is added to the part that is 50% taxable (between the two breakpoints). The maximum amount that is taxable is 85%.
So for certain income levels, there is a sliding scale of the rate of taxability, ranging from 0% up to 85%.