HSA contribution limit

user17672104076 · ‎December 31, 2025

My husband was covered by my employer-provided HSA-eligible HDHP from January through April of 2025. I calculated our allowable family contribution as $8,550 + $1,000 (catch-up for myself) for a total of $9,550 x 4/12 (pro-rating for the 4 months we were on my plan), for a contribution limit of $3,183. I retired at the end of April and went on Medicare. He joined his employer's non-eligible health plan from May through July. He began a new job at the end of July and has been covered by an HSA-eligible HDHP for himself from August 1 through December. I come up with a contribution limit for him of $4,300 + $1,000 (catch-up for himself) for a total of $5,300 x 5/12 (pro-rated for the 5 months on his HDHP) for a contribution limit of $2,208. Since he was covered by his HDHP on Dec 1, can we apply the "Last-Month Rule" to increase his contribution limit to cover the 3 months (May-July) that he was on his non-eligible plan and not covered by my HDHP? Effectively, that would be applying the Last-Month Rule, to 2025 but subtracting the 4 months (Jan-April) that he was covered by my HDHP. Is this calculation correct?

dmertz

I assume that the $3,183 (or at least your $333 catch-up portion of that) was contributed to your HSA, not his. His contributions must be made to his own HSA. Yes, the last-month rule can be applied to allow your husband eligibility for self-only coverage for May through July. However, I think that you failed to account for the fact that using the last-month rule makes him eligible for the full $1,000 catch-up contribution, not just 8/12 of $1,000. His contribution limit without using the last-month rule would be 5/12 of $4,300 plus 9/12 of $1,000 for a total of $2,542, but with the last month rule his contribution limit is $3,867.

Keep in mind that using the last-month rule requires your husband to remain an eligible individual throughout 2026. If there is any month in 2026 that he is not an eligible individual, the $1,325 contributed for May through July will be subject to ordinary income tax and a 10% additional tax on your 2026 tax return.