When you enter your SSA-1099 information into TurboTax, the program will ask if you received a lump-sum Social Security payment.

Answer Yes and follow the instructions. Your SSA-1099 lump-sum section breaks down the payments into what amount was received for each preceding year. You can only enter one year at a time. If you need to enter more than one year, select Add Another Lump Sum if you need to enter benefits received for a different tax year.