Still Contributing to an HSA Near 65? Medicare Timing Deserves Extra Attention

Quick answer: You cannot contribute to an HSA for any month you are enrolled in any part of Medicare, including premium-free Part A alone. If you sign up for Medicare or Social Security after 65, Part A is usually backdated up to 6 months. That is why Medicare.gov advises stopping HSA contributions 6 months before you apply. Money already in your HSA remains yours and can still pay qualified medical expenses, including many Medicare premiums.

Two different questions: contributing versus using

Medicare affects only your ability to contribute new money. It does not affect money already in the account. After you enroll, you can still withdraw HSA funds tax-free for qualified medical expenses. That includes Medicare Part B and Part D premiums, Medicare Advantage premiums and deductibles, copays and coinsurance. Medigap (Medicare Supplement) premiums are not qualified expenses. After 65, withdrawals for non-medical purposes are taxed as income but are no longer subject to the 20% additional tax.

2026 HSA contribution limits

The retroactive Part A rule

If you are 65 or older and sign up for premium-free Part A, coverage generally starts up to 6 months before the month you sign up, but not earlier than the month you turned 65. Applying for Social Security retirement benefits after 65 automatically enrolls you in Part A, with the same backdating. Any HSA contributions made for those retroactive months become excess contributions. Excess contributions not withdrawn in time are subject to a 6% excise tax for each year they remain in the account.

A worked timeline

Hypothetical Pat turned 65 in March 2025, kept working with HSA-eligible self-only coverage from a large employer, and delayed Medicare. Pat plans to retire at the end of 2026 and apply for Medicare Parts A and B in December 2026. The dates and amounts are invented for illustration.

If Pat had kept contributing through December, the contributions for June through December would be excess. They would need to be withdrawn, with any earnings, by the tax-filing deadline to avoid the 6% excise tax. Employer contributions count toward the same limit.

Why delaying Medicare after 65 needs a plan

People who keep working past 65 with coverage from a current employer can often delay Part B without a penalty, and they may choose to delay premium-free Part A to keep making HSA contributions. That choice has three dates to coordinate:

1. When employer coverage ends. That starts your 8-month Special Enrollment Period for Part B. COBRA does not extend it.
2. When Medicare will begin, including any backdated Part A.
3. When HSA contributions stop: 6 months before you apply, per Medicare.gov.

Ask your employer whether its plan requires you to enroll in Medicare at 65. With smaller employers (generally fewer than 20 employees), Medicare usually pays first, and delaying can leave gaps.

Married couples

• Your enrollment in Medicare ends your HSA eligibility, not your spouse's. A younger spouse who is covered by a qualifying HDHP and has no Medicare can still contribute to their own HSA.
• The $1,000 catch-up must go into each eligible spouse's own HSA. There are no joint HSAs.
• Your HSA can pay qualified medical expenses for your spouse, even after you are on Medicare.

Common mistakes

• Applying for Social Security after 65 without realizing it triggers backdated Part A.
• Stopping your own payroll contributions but forgetting the employer's HSA contributions, which count toward the same limit.
• Contributing the full-year limit in the year Medicare starts instead of a prorated amount.
• Assuming Medigap premiums can be paid tax-free from the HSA.
• Delaying Part B on coverage that does not qualify, such as COBRA or retiree coverage, and facing a late penalty.

Frequently asked questions

What to do next

1. Get the Medicare at 65 Checklist. It includes an HSA timing worksheet and an enrollment timeline by birth month.
2. Tell HR and your HSA custodian your planned stop date in writing.
3. Schedule a conversation to coordinate Medicare, HSA and retirement-date decisions.

Related reading: Medicare at 65 · Healthcare before Medicare

Sources

• Medicare.gov — Working past 65 (HSA guidance)
• Medicare.gov — When Medicare coverage starts (retroactive Part A)
• IRS Publication 969 — Health savings accounts
• IRS — Rev. Proc. 2025-19 (2026 HSA limits)

HSA and Medicare rules can create tax consequences. Confirm your enrollment dates and contribution limits with the appropriate professionals before starting or stopping contributions.