On the first screen for entering Social Security benefits, enter the full amount from SSA-1099 box 5 and the other boxes, as indicated on the screen. When you click Continue on that screen, the next screen will ask you if you received lump-sum payments for earlier years. Select Yes and Click Continue. If you have lump sum amounts for more than one year, you enter the information for one prior year at a time. The information on the SSA-1099 tells you what year each lump sum is for. When TurboTax asks you to enter the year, enter one of the years that you got a lump-sum payment for. Continue through the screens entering the information for that year. When you get to the Lump-Sum Social Security Payments Summary screen, if you have a lump-sum for another year that you haven't entered yet, click the button that says "Add Another Lump Sum." Continue entering one year at a time. After you have entered all the years, click Done on the summary screen.