What Happens If You Contribute to an HSA Without an HDHP?

Contributing to an HSA without an HDHP turns your deposit into an excess contribution: you lose the tax deduction, and the IRS charges a 6% excise tax on the ineligible amount every year it sits in the account. The fix is straightforward if you catch it in time. Withdraw the excess (plus any earnings on it) before your tax filing deadline, and the 6% penalty never applies.

Why the Contribution Is Ineligible

HSA eligibility is tested month by month. On the first day of each month you must carry a qualifying HDHP, have no disqualifying additional health coverage, not be enrolled in Medicare, and not be claimed as a dependent on someone else’s return.¹ Miss any one of these for a given month and your eligible contribution for that month is zero. Anything deposited anyway is an excess contribution, and the same label applies to amounts that push you past the annual limit even when you are otherwise eligible.

The Tax Cost of an Ineligible Contribution

Two things happen at once. First, the deduction disappears. If you funded the HSA with after-tax dollars, you can’t deduct the excess on your return. If your employer routed the money through payroll pretax, the amount gets added back to your gross income.¹

Second, the IRS charges a 6% excise tax on any excess contribution still in the account at year-end.² The tax recurs every year the excess remains. A $5,000 ineligible contribution costs $300 the first year, another $300 the second year, and it keeps compounding until the excess is removed or absorbed. You report the excise tax on Form 5329.¹ The tax is capped at 6% of the total year-end account value, which mainly matters in edge cases where the excess has outgrown the balance.

Fixing It Before Your Filing Deadline

The cheapest correction is withdrawing the money before the due date of your return, including extensions. That’s typically April 15 of the following year, or later with an extension.³ Take the excess out in time and the 6% excise tax never applies.

Call your HSA custodian and request a “return of excess contribution.” You have to pull out the ineligible principal and any earnings it generated while sitting in the account. The custodian calculates those attributable earnings and reports the withdrawal on Form 1099-SA with distribution code 2.⁴

The principal isn’t taxed a second time on the way out; you already lost the deduction, or the amount was already added back to your income. The attributable earnings are taxable as ordinary income in the year you receive them, but they escape the 20% additional tax that normally hits non-qualified HSA withdrawals, provided you follow the correction process.⁵

File Form 8889 with your return for the contribution year to report the excess and its withdrawal.⁶ A timely correction costs you only the income tax on whatever small amount of earnings the excess produced.

Already Filed? You Still Have Six Months

If you filed on time but forgot to pull the excess first, the IRS gives you a second chance. You can make the withdrawal up to six months after the original due date of the return, not counting extensions. To use this window, file an amended return with “Filed pursuant to section 301.9100-2” written at the top, include an explanation of the withdrawal, and attach an amended Form 5329 showing the contributions are no longer treated as excess.³

Fixing It After Both Windows Close

Miss the filing deadline and the six-month backstop, and the 6% excise tax for the contribution year is locked in. Pay it by filing Form 5329 for that year. If you claimed a deduction for the ineligible contribution on your original return, file Form 1040-X to add the amount back to your gross income.³

The 6% keeps recurring for every subsequent year-end the excess is still in the account. You have two ways to make it stop.

The first is to simply withdraw the money. That ends future 6% assessments but doesn’t erase what you already owe for prior years, and because the withdrawal happens outside the correction window, it’s treated as a regular distribution: tax-free if spent on qualified medical expenses, otherwise included in income and subject to the 20% additional tax (waived after age 65 or disability).⁷

The second is to absorb the excess in a future year. If you regain HSA eligibility, you can under-contribute in a later year and let the leftover excess fill the gap. The amount that gets absorbed equals the lesser of your remaining room (annual limit minus current-year contributions) or the total excess still in the account.¹ Once absorbed, the excise tax stops. This route only makes sense if you expect HDHP coverage back soon; every year you wait costs another 6%.

Eligibility Traps That Cause This

People often contribute in good faith and discover only later that something disqualified them.

A general-purpose Flexible Spending Account through your employer or your spouse’s employer counts as disqualifying coverage. Limited-purpose FSAs that cover only dental and vision are the exception. TRICARE also counts as disqualifying; the Department of Defense does not classify it as an HDHP.⁸

Medicare is the biggest trap for people working past 65. When you enroll in Medicare Part A after 65, coverage applies retroactively for up to six months before your enrollment date. That retroactive coverage invalidates any HSA contributions you made during those months. If you plan to keep contributing past 65, stop contributions at least six months before you enroll in Medicare or start collecting Social Security, which triggers automatic Part A enrollment.¹

You Can Still Use the HSA

Losing HDHP coverage doesn’t freeze the account. You can withdraw money at any time and spend it tax-free on qualified medical expenses regardless of your current health plan. The HDHP requirement governs contributions, not distributions.¹ Investments keep growing tax-free, and the account stays open.

Non-medical withdrawals are included in your gross income and hit with a 20% additional tax. The 20% penalty falls away at age 65 or on disability, though the income tax still applies.⁷

A Related Trap: The Last-Month Rule Recapture

The last-month rule lets you contribute the full annual amount if you have HDHP coverage on December 1, even if you weren’t covered the whole year. The catch is a testing period running from December 1 of that year through December 31 of the following year; you must keep HDHP eligibility every month.¹

If you lose HDHP coverage during the testing period for any reason other than death or disability, the amount you contributed beyond the prorated monthly calculation gets added back to your gross income, and you owe a 10% additional tax on it.³ Report both through Part III of Form 8889. This recapture is separate from the 6% excise tax and applies in the year you fail the testing period, not the year you originally contributed. If there’s any chance you won’t hold HDHP coverage through the full testing period, use the prorated monthly calculation instead of the last-month shortcut.

Watch Your State Return

A few states with income taxes don’t recognize the federal HSA deduction. California and New Jersey are the most notable: residents owe state income tax on HSA contributions regardless of federal treatment. An excess contribution corrected at the federal level may still need separate handling on your state return. If you file in a state that doesn’t recognize HSAs, check with your state tax authority or a tax professional on the state reporting.

1
Internal Revenue Service. Publication 969 (2025), Health Savings Accounts and Other Tax-Favored Health Plans
2
Office of the Law Revision Counsel. 26 U.S. Code 4973 – Tax on Excess Contributions to Certain Tax-Favored Accounts
3
Internal Revenue Service. Instructions for Form 8889 (2025)
4
Internal Revenue Service. Instructions for Forms 1099-SA and 5498-SA (Rev. December 2026)
5
Internal Revenue Service. Instructions for Form 5329 (2025)
6
Internal Revenue Service. About Form 8889, Health Savings Accounts (HSAs)
7
Office of the Law Revision Counsel. 26 U.S. Code 223 – Health Savings Accounts
8
TRICARE. Do Health Savings Accounts Work With TRICARE?