Medicare & HSA Eligibility

There is often confusion about whether turning 65, enrolling in Medicare, or having a spouse covered by Medicare affects HSA eligibility. This summary outlines HSA eligibility, HSA contribution limits, and the impact of Medicare entitlement

HSA Eligibility

HSA eligibility is based on three factors:

• Enrollment in a qualifying high-deductible health plan (HDHP);
• No other “disqualifying coverage” (e.g., Medicare); and
• Not being able to be claimed as a tax dependent by another individual.

Eligibility for an HSA is determined monthly based on the coverage in effect as of the 1st of the month.

It is also important to note that HSA eligibility and HDHP eligibility are two different things; an individual who is not HSA eligible may still be eligible for the underlying HDHP. Eligibility for the HDHP will depend on eligibility rules set by the plan sponsor or carrier, whereas eligibility for an HSA is determined by federal laws and regulations. Neither Medicare eligibility nor Medicare entitlement will cause a loss of eligibility for HDHP coverage unless the employer’s plan specifically excludes Medicare-eligible or entitled individuals (and most will not due to Medicare Secondary Payer rules).

HSA Contribution Rules

Individuals may make a maximum annual contribution to their HSA according to statutory limits (indexed annually) based on their level of HDHP coverage:

Type of HDHP Coverage	2025	2026
Single	$4,300	$4,400
Family (other than single)	$8,550	$8,750

Additional annual “catch-up” contributions of up to $1,000 (prorated based on monthly eligibility) are permitted for individuals who are 55 or older by the end of the calendar year.

Annual contribution limits and catch-up contributions for an individual are prorated based on how many months of the calendar year the individual is HSA-eligible – 1/12 of the annual maximum for each eligible month of coverage (determined as of the 1st of each month).

Contributions for a calendar year may be made up until the tax filing deadline for the year (typically April of the following year), and once contributions are made to an HSA, they remain available for qualifying medical expenses even after the loss of HSA eligibility.

Medicare Eligibility vs. Medicare Entitlement

It’s important to distinguish between “eligibility for” and “entitlement to” (i.e., enrollment in) Medicare. Merely being eligible for Medicare does not make somebody ineligible to establish/contribute to an HSA. Therefore, simply turning 65 does not interfere with a person’s HSA eligibility if the individual delays enrollment in Medicare. However, individuals who become entitled to (i.e., who enroll in) Medicare become ineligible for an HSA as of the first month that Medicare coverage is effective.

Medicare Part A enrollment is automatic for some individuals (i.e., those who are already receiving Social Security benefits when they turn 65). These individuals simultaneously become eligible and enrolled upon reaching age 65 and thus become ineligible for an HSA. Choosing not to enroll in Part B does not help; Part A enrollment alone makes an individual ineligible for an HSA. Other individuals that are not receiving Social Security benefits will merely become eligible for Medicare upon reaching age 65 and must take the additional steps to become enrolled in Medicare benefits.

• Situation: Gerry turns 65 and becomes eligible for Medicare based on age. However, he delays his application for Social Security because he is still employed and has access to health insurance through his employer. Therefore, he does not become entitled to (enrolled in) Medicare.
• Analysis: Gerry’s eligibility for Medicare does not interfere with HSA-eligibility. If he is otherwise eligible to contribute to an HSA, he may do so until he enrolls in (i.e., becomes entitled to) Medicare.

Employees who have coverage under an employer-sponsored plan may want to delay Medicare enrollment for things such as maintaining eligibility to contribute to an HSA. But keep in mind that if entitlement to Medicare is delayed, then once a person is enrolled, Medicare benefits are generally retroactive up to 6 months (up to the date that the individual became eligible for Medicare), which means HSA ineligibility would be retroactive as well. In this case, it is advisable to either cease making any contributions prior to enrolling in Medicare or contribute only up to the applicable prorated contribution limit.

• Situation: Antonio is enrolled in single coverage under his employer’s HDHP. He is HSA-eligible and contributes to an HSA. Antonio turns 65 in June 2025 but delayed Medicare entitlement because he continues to work. In February of 2026, Antonio retires and applies for Medicare. His application is approved in March, and his effective date is backdated 6 months to October 1, 2025.
• Analysis: Antonio was HSA-eligible for 9 months during 2025 and is eligible to make a maximum contribution of [($4,300 + $1,000)/12] for each of his 9 eligible months, calculated as [($5,300/12) x 9] = $3,975 for his annual HSA contribution limit for 2025. He has until the tax filing deadline in April of 2026 to make his contributions for 2025.

Mid-Year Medicare Entitlement

For an employee who begins the year contributing to an HSA, there are some considerations that arise if that employee subsequently enrolls in Medicare and loses HSA eligibility. Upon losing HSA eligibility mid-year, the safest approach is to stop all employer and employee contributions, but that isn’t always necessary.

If the employee does not exceed their prorated HSA contribution limit, it is permissible to continue contributing for the remainder of the year (beyond the loss of HSA eligibility). The mid-year loss of eligibility affects the total annual amount that may be contributed, but not the timing. However, if the employee exceeds their prorated HSA contribution limit, then they will need to request a curative distribution before the tax filing deadline to avoid the 6% excise tax that applies to excess contributions.

• Situation: Alex is enrolled in single HDHP coverage through her employer for the entire 2025 calendar year and contributes $50 per month to her HSA. She turns 65 in July 2025 and has Medicare coverage effective as of August 1, 2025. She continues contributing $50 per month to her HSA.
• Analysis: Because she is HSA eligible for 7 months out of the year, Alex’s HSA contribution limit for 2025 will be [($5,300/12) x 7] = $3,091.67. At $50 per month, Alex would have contributed $50 x 12 = $600 in 2025, which is less than her prorated HSA contribution limit. Since she did not exceed her prorated limit, Alex does not need to stop her contributions upon losing HSA eligibility and has no excess contributions to worry about.

Following a loss of HSA eligibility, any funds that have already been contributed to the HSA remain available to use for qualifying medical expenses incurred by the HSA account holder as well as the account holder’s spouse and tax dependents.

Spouses’ Medicare Entitlement

A spouse’s Medicare entitlement (and resulting HSA ineligibility) does not impact the employee’s HSA eligibility or ability to contribute to an HSA if the employee is otherwise eligible to do so. If the spouse (or other dependent) remains enrolled on the employee’s HDHP, then the employee will still be able to contribute up to the family annual contribution limit. Moreover, funds from the employee’s HSA may still be used to reimburse the HSA-ineligible spouse’s qualifying medical expenses.

• Situation: Kate is 56, is enrolled in family HDHP coverage through her employer, and is eligible as of January 1, 2026, to contribute to an HSA. In July 2026, her spouse becomes entitled to Medicare.
• Analysis: As long as Kate remains HSA eligible, her spouse’s Medicare entitlement has no effect on her ability to contribute to an HSA. Funds from Kate’s HSA may also still be used to reimburse her spouse’s qualifying medical expenses. If Kate remains on the family plan throughout 2026, she may contribute the full family contribution maximum and catch-up contribution of $9,750, and she has until the tax filing deadline (mid- April 2027) to make these contributions.

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