The HSA contribution deadline and prior-year deposits
Make a prior-year contribution by the federal return due date and ensure the custodian codes it to the intended year.
HSA contributions for a tax year generally may be made through the unextended federal income tax return due date. Filing an extension does not extend the HSA contribution deadline.
Recalculate the prior-year room
The later funding window does not create eligibility. Use that year's monthly coverage, employer deposits, and catch-up status, then subtract all contributions already assigned to the year.
Verify the custodian's designation
Transfer screens may default to the current year. Save confirmation showing the intended year and inspect Form 5498-SA. Correct a miscoded contribution with the custodian instead of adjusting only the return.
Example and common mistake
A taxpayer funds the prior year's HSA in March but leaves the transfer set to the current year. Custodian reporting and the deduction diverge. The mistake is assuming the payment date tells the custodian which year was intended.
Control the tax-year designation
Before transmitting a contribution after December 31, select the intended prior tax year in the custodian's system and save the confirmation. Verify that the deposit settles by the federal return filing deadline, excluding extensions. A return extension does not extend the HSA contribution deadline.
After Form 5498-SA becomes available, reconcile its contribution-year reporting with the return and request a correction if the custodian used the wrong year. Also include late-posted employer or payroll amounts in the annual limit. The bank transaction date alone does not prove how the custodian reported the deposit.
Questions to resolve
- Did the deposit settle by the unextended filing deadline?
- Which tax year appears on the custodian confirmation?
- Does Form 5498-SA ultimately agree with the return workpaper?
Federal authority record
- U.S. House Office of the Law Revision Counsel: 26 U.S.C. section 223 - Health savings accounts
HSA eligibility, contribution limits, qualified distributions, and beneficiary rules - IRS: Publication 969 — HSAs and other tax-favored health plans
Monthly eligibility, last-month rule, spouses, Medicare, and excess contributions - IRS: Instructions for Form 8889
HSA contribution, deduction, distribution, excess, and filing rules