Overview
A Health Savings Account (HSA) offers a rare triple tax advantage: contributions are pre-tax, growth is tax-free, and withdrawals for qualified medical expenses are tax-free. But HSAs have a hard rule that trips up a lot of retirees: you cannot contribute once you're enrolled in any part of Medicare — and Medicare enrollment can be triggered retroactively.
Why It Matters
The years right before Medicare eligibility are the last window to max out HSA contributions, and the account remains useful well into retirement — funds can be withdrawn tax-free for medical expenses at any age, including Medicare premiums (though not Medigap premiums) once you're on Medicare. Getting the contribution timing wrong, however, can trigger an IRS excess-contribution penalty.
How It Works
- To contribute to an HSA, you must be enrolled in a qualifying High-Deductible Health Plan (HDHP) and have no other disqualifying coverage — including Medicare.
- The retroactive trap: if you delay applying for Medicare past 65 but are already collecting Social Security, Medicare Part A coverage is applied retroactively up to 6 months (but not before your 65th birthday). Any HSA contributions made during that retroactive window become excess contributions subject to a 6% excise tax per year until corrected.
- The safe move: stop HSA contributions 6 months before your planned Medicare enrollment date (or 6 months before turning 65 if you plan to file for Social Security at 65).
- OBBBA expanded HSA eligibility starting 2026 to include people on Bronze and Catastrophic ACA marketplace plans, which weren't previously HSA-qualified.
2026 Key Numbers
- Contribution limits: $4,400 self-only / $8,750 family for 2026.
- Minimum HDHP deductible: $1,700 self-only / $3,400 family.
- Catch-up contribution (55+): an additional $1,000/year, available until Medicare enrollment.
- OBBBA also expanded qualifying expenses to include some direct primary care arrangements and telehealth.
Common Mistakes
- Continuing HSA contributions after applying for Social Security at or after 65, not realizing Medicare Part A applies retroactively
- Forgetting the 55+ catch-up contribution stops the moment Medicare coverage begins, even mid-year — requiring a prorated contribution limit for that year
- Not using HSA funds for Medicare Part B, Part D, or Medicare Advantage premiums, which are qualified expenses (Medigap premiums are not)
- Treating the HSA as a spend-it-or-lose-it account — unlike an FSA, HSA balances roll over indefinitely and can be invested for long-term growth
Sources
- IRS Notice 2026-05 — OBBBA changes to HSA rules (irs.gov)
- HealthCareInsider — HSA Changes 2026: New Rules, Contribution Limits
- IRS Publication 969 — Health Savings Accounts and Other Tax-Favored Health Plans
This is general education, not personalized advice. Coordinate HSA contribution stop dates with your specific Medicare and Social Security filing timeline with a benefits specialist.