You enrolled in an HDHP in January and started maxing your HSA. In June, your spouse’s open enrollment opens and the family signs onto a richer PPO plan. Your HDHP coverage ends. Now what?
The short version: your HSA itself is fine. The money is yours forever. But the contribution math changes, and if you’ve already contributed the full year limit, you might have an excess contribution problem you didn’t realize you had.
Your HSA Account Doesn’t Care About Coverage
The account is yours. It doesn’t get closed, it doesn’t get frozen, the balance doesn’t transfer anywhere. You can still spend it on qualified medical expenses tax-free. You can still let it grow invested. None of that changes when your coverage changes.
What changes is your ability to contribute. To put new money into an HSA, you need to be enrolled in a qualifying HDHP. The day you drop HDHP coverage is the day new contributions stop being eligible (with one exception we’ll get to).
The Prorated Contribution Limit
For 2026 the HSA contribution limits are roughly $4,150 self-only and $8,300 family (these numbers go up slightly each year). If you have HDHP coverage all 12 months, you can contribute the full amount.
If you only have HDHP coverage for part of the year, your limit gets prorated by the number of full months of HDHP coverage. Coverage as of the first day of the month counts the whole month.
Example: You have HDHP coverage from January 1 through May 31, then switch to PPO on June 1. That’s 5 full months of HDHP coverage. Your prorated limit:
- Self-only: $4,150 × 5/12 = $1,729
- Family: $8,300 × 5/12 = $3,458
If you already contributed $4,150 in those first five months thinking you’d be HDHP all year, you have an excess contribution of $2,421. That excess gets a 6% penalty per year until you fix it.
How to Fix an Excess Contribution
You have two options:
- Withdraw the excess plus earnings by your tax deadline. The excess comes out tax-free; the earnings on it get taxed as ordinary income that year. No 6% penalty. Most HSA custodians have a “return of excess contribution” form for this.
- Leave it and pay the 6% penalty. If your contribution limit goes back up next year (you go back to HDHP), the excess can be absorbed. But each year it sits as excess, you pay 6% on Form 5329.
For most people switching plans mid-year, option 1 is cleaner. Call your HSA custodian as soon as you know about the coverage change.
The Last-Month Rule (and Why It Bites People)
Here’s the exception. If you have HDHP coverage on December 1, you can contribute the full annual limit, even if you didn’t have HDHP coverage all year. This is called the last-month rule.
The trap: this only works if you stay in the HDHP through the next December (the testing period). If you take the last-month rule benefit in December 2026 and then switch to a PPO in March 2027, you have to recapture the contributions you made above the prorated limit. They become taxable income plus a 10% penalty.
This catches people who use the last-month rule strategically and then change jobs or get married and end up on a spouse’s PPO. The IRS doesn’t care that life happened. The penalty applies.
What If You Get HDHP Coverage Mid-Year (Reverse Direction)
Going PPO → HDHP mid-year works the same way. You prorate by months of HDHP coverage starting from the first month of HDHP enrollment. The last-month rule still applies if you’re enrolled in HDHP on December 1.
So if you switch to HDHP on October 1 and stay enrolled through December 1, you can either:
- Use the prorated limit (3 months × full annual ÷ 12)
- Use the last-month rule and contribute the full annual limit, with a testing period requirement to stay HDHP through next December
Most people in this scenario use the last-month rule because it lets them catch up on the year’s contributions, but you have to actually stay in HDHP next year too.
Common Specific Scenarios
You and your spouse both have HDHP, one switches to PPO
If your HDHP covers your spouse and they switch to a PPO that doesn’t, your family HDHP becomes self-only HDHP from that month forward. Your contribution limit for the remaining months goes from family to self-only level.
You switch to a spouse’s PPO that covers you
Once you have any non-HDHP coverage, you stop being HSA-eligible. If your spouse’s PPO covers you starting June 1, your HSA contribution eligibility ends May 31.
You drop coverage to none (uninsured)
Believe it or not, being uninsured doesn’t make you HSA-ineligible. You’re ineligible because of other health coverage, not lack of HDHP. So if you drop your HDHP and have no replacement, you can’t contribute (no qualifying HDHP), but you didn’t trigger ineligibility for being on a PPO.
FSA and HSA together
This is where most mid-year mistakes happen. If your spouse signs up for a regular healthcare FSA (not a limited-purpose FSA), you become HSA-ineligible the moment that FSA covers you. The FSA is treated as “other health coverage” because it can pay for general medical expenses. People miss this all the time.
What to Do Right Now If You Already Switched
- Look at the date your HDHP coverage actually ended. (Not when you signed up for the new plan, but when the old one stopped.)
- Count full months of HDHP coverage in the calendar year. The first day of the month rule matters.
- Calculate your prorated limit.
- Compare to what you’ve actually contributed. If you’re over, request a return of excess contribution.
- Don’t make any more HSA contributions until you’ve worked this out.
For Future Open Enrollment
If you’re someone who hops between HDHP and PPO based on year-to-year health expectations, keep one rule in mind: plan around January 1 and December 1. If you have HDHP on December 1 and stay through next year, the math is clean. If you change in the middle of the year, you’re dealing with prorations and possible recapture.
For a related question on retirement-account interactions, the backdoor Roth pro-rata rule piece covers another tax-advantaged account where mid-year mistakes create lasting headaches.
The HSA is one of the best tax-advantaged accounts in the code. Triple tax benefit, no use-it-or-lose-it, portable through job changes. The only thing that trips people up is the contribution rules around coverage changes. Get those right and everything else takes care of itself.