Retirement: full retirement age is 67 for anyone born in 1960 or later. Benefits can start as early as 62, permanently reduced. Requires 40 credits (fully insured).

Medicare: generally starts at 65; people with a disability or end-stage renal disease can qualify earlier. Per the CDI outline, 40 credits gives premium-free Part A and eligibility for Part B (Part B has a premium).

Disability: the condition must keep the worker from substantial work and be expected to last at least 12 months or result in death. Benefits begin after a waiting period of 5 full months. Work tests: a recent-work test (before 24: 6 credits in the 3 years before the disability; 24 to 31: credit for half the time since 21; 31 or older: generally 20 credits in the last 10 years) plus a duration-of-work test. The CDI outline calls the under-24 rule currently insured status.

Survivors: monthly benefits to a surviving spouse caring for the worker's child under 16 (or disabled); a widow(er) from 60 (50 if disabled); unmarried children under 18 (up to 19 if still in K-12 full time, any age if disabled before 22); dependent parents 62 or older. A one-time $255 lump-sum death payment may go to the spouse or certain minor children.

Fully insured: 40 credits. Survivors may need fewer, depending on the worker's age at death.

Currently insured: at least 6 credits in the 13-quarter period ending with the quarter of death. This lets the children, and a spouse caring for them, collect even if the worker was not fully insured.