Still Working at 67 with HDHP: How to Delay Medicare Without Losing HSA Room

Sample case: 67-year-old executive at a 5,000-employee company, on the company's HSA-eligible HDHP, $9,300 family HSA contribution annually with employer match. Wants to keep contributing for two more years until full retirement at 69.

The trap

Filing for Social Security benefits at any age 65+ automatically enrolls you in Medicare Part A. Once Part A starts, HSA contributions must stop. Many late-career workers file for Social Security at 67 (full retirement age) without realizing this kills the HSA.

The fix: delay both

Do not file for Social Security yet. Do not enroll in any part of Medicare. Because the employer has 20+ employees, the employer plan is primary insurance and you have no Medicare gap. The Special Enrollment Period gives you 8 months to sign up for Medicare after employer coverage ends, with no penalty.

Verify employer letter annually

SSA may send IRMAA-style letters anyway because you are 65+. File Form CMS-L564 (request for employment information) annually so the employer's HR confirms your active coverage. This documentation prevents Part B late-enrollment penalties when you finally do enroll.

Six-month lookback warning

When you do enroll in Medicare (say at age 69), Part A coverage backdates by six months. So if you enroll in March 2028, Part A starts September 2027. Any HSA contributions made September 2027 to March 2028 become excess contributions, subject to 6% excise tax per year until withdrawn. To avoid this, stop HSA contributions exactly six months before your planned enrollment date.

The retroactive Social Security trap

If you file for Social Security at 70 to maximize benefits, you can ask SSA for retroactive benefits, up to six months back. Doing so triggers retroactive Medicare Part A as well, which can wipe out HSA contributions. Skip the retroactive request if HSA matters.

Two-year HSA savings

$9,300/year × 2 years = $18,600 of pre-tax savings. At a 32% marginal bracket that is $5,952 of federal tax avoided. Not enrolling in Medicare also keeps an extra $5,000 of payroll Medicare premium spending out of pocket for those two years. Total: about $11,000 better off vs the default "file at 65" path.