If you e-filed the tax return, there are no paper forms included with the e-filed tax return.
If the tax return was printed and mailed, then only forms with taxes withheld would be included with the mailed return.
Did you have federal income taxes withheld from the Social Security benefits? If so, those taxes withheld were on the SSA-1099 in box 6 and would have been entered on the Form 1040 as a tax payment on Line 25b.
