Personal Finance & Estate › Medicare, Medi-Cal & long-term care › Medicare (federal health insurance at 65+)
Medicare enrollment windows & late penalties
Opens 3 months before 65· Government program
Watch outA common mistake, trap or scam.
The sign-up windows for Medicare around age 65, and the lifelong penalties for missing them without qualifying job coverage.
See it on the Personal Finance & Estate map →How it works
Your initial window runs seven months: three before your 65th-birthday month, that month, and three after. If you or your spouse still work with employer coverage (generally 20+ employees), you can delay Part B and use an eight-month special window once that job or coverage ends. Otherwise the Part B penalty is 10% for each year late, for life; Part D adds 1% per month. Red flag: COBRA and retiree coverage don't count. Protect parents: calendar it a year ahead and call HICAP.
Why it matters for you
Missing it is one of the costliest and most common Medicare mistakes, and the penalty never goes away.
Red flags and protection
The Social Security Act and CMS rules; the 'Medicare & You' handbook and SSA, which handles sign-ups, publish the windows. A 2023 change made coverage start the month after you sign up.
Watch out for
Relief for people misled by employers or agents exists but is narrow and decided case by case.
Connections (5)
▸Medicare enrollment windows & late penalties control entry into Medicare (federal health insurance at 65+)Watch out
How they connect
You join Medicare by signing up for Parts A and B during set windows. Miss your initial or special window without qualifying job coverage, and you wait for the January–March general window and can owe a lifetime Part B surcharge.
When it applies
The windows and the 10% Part B penalty date to Medicare's early years; a 2023 change ended long waits after general enrollment.
How sure?
Sections 1837–1839 of the Social Security Act and CMS's 'Medicare & You' handbook; penalties appear on premium notices.
Watch out for
How often people miss enrollment unknowingly is poorly tracked; advocates push for clearer notices before 65.
▸Full retirement age (67 if born 1960 or later) no longer lines up with Medicare enrollment windows & late penaltiesWatch out
How they connect
Medicare starts at 65, but full Social Security now comes at 67. When both began at 65, many signed up together; now anyone not yet collecting Social Security must actively enroll in Medicare at 65, or risk coverage gaps and lifelong penalties.
When it applies
The gap opened as the 1983 law phased full retirement age up from 65, starting with people born in 1938; Medicare's age stayed at 65.
How sure?
SSA and CMS both warn that delaying Social Security does not delay Medicare deadlines.
Watch out for
Some propose raising Medicare's age to match; others say that would shift costs to employers and individuals.
▸Social Security Administration (SSA) handles sign-ups for Medicare enrollment windows & late penaltiesLaw or rule (2026)
How they connect
Although CMS runs Medicare, SSA processes enrollment in Parts A and B. People already collecting Social Security at 65 are enrolled automatically; everyone else must apply through SSA, online or by phone. SSA also verifies employer coverage for late sign-ups and deducts Part B premiums from benefit checks.
When it applies
SSA field offices have handled Medicare enrollment since the program began in July 1966; the Railroad Retirement Board handles rail workers.
The rule
Federal rules (42 CFR Part 407) set the enrollment process; SSA processes Form CMS-L564, the employer-coverage form required for late Part B sign-ups.
Watch out for
With SSA offices short-staffed, how often processing delays cause coverage gaps or wrongful penalties is unclear; keeping proof of every filing helps.
▸Medicare enrollment windows & late penalties are not paused by COBRA & Cal-COBRA continuation coverageWatch out
How they connect
COBRA keeps your old job's coverage but does not count as current employment for Medicare. Your eight-month Part B window starts when the job ends, not when COBRA ends. Wait for COBRA to run out and you can face penalties and gaps, since Medicare pays first.
When it applies
Part of Medicare's Part B special-enrollment rules; Cal-COBRA, California's extension for small employers, works the same way.
How sure?
CMS and Medicare.gov state explicitly that COBRA and retiree coverage do not qualify for the special enrollment period.
Watch out for
CMS has occasionally granted relief to people misled about COBRA, but it is rare; do not count on it.
▸HICAP (free California Medicare counseling) guides choices during Medicare enrollment windows & late penaltiesStandard practice
How they connect
Before 65, HICAP counselors check whether your job coverage lets you safely delay Part B, explain Medigap timing and California's birthday rule, and help request corrections when penalties were applied in error.
When it applies
Free statewide, year-round for people turning 65, with peak demand during the October 15–December 7 open enrollment.
How sure?
CMS lists state SHIP programs like HICAP as official, unbiased enrollment help in its 'Medicare & You' handbook.
Watch out for
Counselors explain options but don't decide for you; complex employer or COBRA cases may also need HR or a benefits attorney.