You do not report this. According to the IRS, Supplemental Security Income (SSI) is not taxable and should not be included on your tax return at all. You will not receive a Form 1099 for these payments.
If you are referring to Social Security Income, that is different and should be reported. Navigate to Federal > Wages & Income > Wages & Income Summary > Add more income > Retirement Plans and Social Security > Social Security (SSA-1099, RRB-1099)
