Can I report estimated SSA income without the SSA-1099 form?
Did you not receive your SSA1099? Or did you lose it? Social Security mails them in January.
GET SSA1099
https://www.ssa.gov/faqs/en/questions/KA-01723.html
Go to Federal> Wages & Income>>Retirement Plans and Social Security (SSA1099 and 1099RRB) to enter your SSA1099.