Answer:

You can't amend returns for prior years to reflect Social Security benefits received in a single lump-sum in the current year. You must include the taxable part of a lump-sum payment of benefits received in the current year (reported to you on Form SSA-1099, Social Security Benefit Statement) in your current year's income, even if the payment includes benefits for an earlier year.

However, there are two ways to determine the amount of income to include:

You can use your current year's income to figure the taxable part of the total benefits received in the current year; or

You may make an election to figure the taxable part of a lump-sum payment for an earlier year separately, using your income for the earlier year.

You can select the lump-sum election method (by checking the box on line 6c of your Form 1040 or 1040-SR ) if it lowers the taxable portion of your benefits:

Under this method, you refigure the taxable part of all your benefits (including the lump-sum payment) for the earlier year 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).

Worksheets in Publication 915, Social Security and Equivalent Railroad Retirement Benefits can help you calculate the taxable portion using this method.