Boxes 2, 3 and 4 are not required to be entered.
Box 2 is for the Social Security number of the payee and this information is already in your return when you enter the amount from box 5 under the name of the person receiving the benefits.
Box 3 and 4 are not entered since the amount in box 5 is box 3 minus box 4.
Box 6 is only used if federal income taxes were withheld and is available on the screen where entering the box 5 amount.
If the Social Security number in box 2 is the same for the both of the SSA-1099's received you add the amounts in box 5 together and enter the sum on the TurboTax form SSA-1099.
