Zelda retired from the railroad after 45 years of service at age 70 in 2021 . She is a widow and files as single. She received a Form RRB-1099 with $16,500 in box 5 . She received a Form RRB-1099-R with $19,222 in box 7 and reports it on line 5b of her Form 1040/1040SR. She received no other taxable income. Up to of her Tier 1 benefits may be taxable. 0% 50% 85% 100%