You can use the "lump-sum election" on your tax return, which should significantly reduce your tax. It calculates how much of the benefit for each past year would have been taxable if you had reported it in that year, and then reports that amount as taxable on your 2024 tax return. On Form 1040 the box on line 6c will be checked, indicating that you used the lump-sum election.
When you enter your Form SSA-1099 in TurboTax, enter the full box 5 amount, and any other information from the SSA-1099, then click Continue. Two screens later it will ask whether you received a lump-sum payment. Select Yes and continue through the questions. You will need your tax returns for the earlier years. Enter the information for one prior year at a time. It doesn't matter what order you enter them in. After you answer all the questions for the first prior year you will come to a summary screen that says "Here's your lump-sum payment info." On that screen click the button at the bottom that says "Add another lump sum payment" and go through the same questions for the next year. Repeat this until you have entered all the prior years, then click Done on the summary screen.
This answer has been verified for accuracy by an Intuit expert employee
