Get your taxes done using TurboTax

Hi @msjrice 

Generally, you use your current year income to figure the taxable part of the total benefits received in that year.  

For those with additional sources of income, the key figure is the Modified Adjusted Gross Income (MAGI). The MAGI includes half of your Social Security, plus other sources of income. Once your MAGI exceeds the base amount for your filing status ($32,000 for Married Filing Jointly or $25,000 for all others), at least part of your Social Security income becomes taxable. The taxable portion of your Social Security income increases once you reach additional MAGI thresholds.

At the state level, many states exempt Social Security from taxation, either partially or completely. Again, if your sole income is from Social Security, it's likely you don't need to file a state return either.

Enter your Social Security income into TurboTax, and we'll tell you if it's taxable.

Please also note, you may be able to figure the taxable part of a lump-sum payment for an earlier year separately, using your income for the earlier year. You can elect this method if it lowers
your taxable benefits.
Under the lump-sum election method, you refigure the taxable part of all your benefits for the earlier year (including the lump-sum payment) using that year's income. Then, you subtract any taxable benefits for that year that you previously reported. The remainder is the taxable part of the lump-sum payment. Add it to the taxable part of your benefits for the current year (figured without the lump-sum payment for the earlier year).

Here is useful link regarding Social Security and Back Payments: 

Back Payments