An FSA balance has a clock on it. An HSA balance does not. Almost everything below is really about the first one — and the single most valuable thing on this page is the part that tells you what not to spend it on.
Prints clean, with the boxes intact.
Before the list: the December trap
Every year, the last fortnight of December produces a wave of advice to empty an FSA balance into the supplement aisle. Most supplements are not eligible — the exception in Pub. 502 requires a practitioner to recommend the item as treatment and a physician to have diagnosed a specific condition for it to treat. In IR-2024-65 the IRS warned specifically about companies selling doctor’s notes to paper over that gap. A rushed December purchase against a letter you bought online is the worst version of this.
Spend the balance in the categories where the authority is actually clean. They are listed below, in order.
Confirm whether you hold an HSA, a health FSA, or both — some people carry an HSA plus a limited-purpose FSA. Every deadline below applies to one and not the other.
Find your plan year end date. Many plans run on the calendar year. Many do not. If yours does not, shift every date on this page.
Find out which relief your FSA offers: a 2½-month grace period or a carryover. Your plan may offer either — never both.
Find your run-out period. It extends the window to file a claim for an expense already incurred. It does not extend the window in which the expense may be incurred. People lose money on this distinction every year.
Pull your year-to-date balance and your year-to-date contributions. Write both numbers down; everything after this is arithmetic against them.
1 October – 30 November 2026
Open enrollment, and an election based on evidence rather than hope
Your employer sets its own open enrollment window — watch for the notice rather than assuming a date.
Add up what you actually spent this year on things that were reimbursed without an argument: copays, prescriptions, over-the-counter drugs, monitors, lab panels. That number is your election for next year — not the number you wish you had spent on wellness.
For reference, the 2026 health FSA salary-reduction limit is $3,400 with a maximum carryover of $680 (Rev. Proc. 2025-32). The following year's figures come from a separate revenue procedure — check it rather than assuming this year's number carries forward.
HSA holders: the 2026 contribution limits are $4,400 self-only and $8,750 family, plus a $1,000 catch-up from age 55 (Rev. Proc. 2025-19). Note the date on the next line before you rush.
The HSA contribution deadline is not in December. It is April 15, 2027 — the unextended due date of the return. Filing an extension does not extend it.
1 – 15 December 2026
Spend the FSA on things that are actually eligible
This is the point in the year where the internet tells you to buy supplements with your FSA. Read the warning on the guide again before you do. Most supplements are not eligible, and IR-2024-65 exists because of how aggressively that gets sold every December.
Start with the uncontroversial core: doctor visits, copays, prescriptions. The reference data scores this category yes on all three tests.
Monitors and diagnostic devices — the cleanest authority in the whole framework, and eligible regardless of prescription status.
Lab panels — a plain panel is the easy case; a bundled consumer kit raises an allocation question worth asking your administrator about first.
If you think you need a letter for something, book the appointment now. A letter requires a clinician who has actually evaluated you, and December is a poor month to get onto anyone's schedule. Magellan does not provide letters and cannot arrange one.
16 – 31 December 2026
The incurred-by date, and the receipts
For an FSA, the expense generally has to be incurred within the plan year — or within the grace period, if your plan has one. Ordering on 30 December and receiving the parcel on 6 January raises a question about which date counts: ask your administrator how they date it rather than guessing.
Photograph every receipt. Itemised, legible, with the product name on it. "Pharmacy — $61.40" substantiates nothing.
Keep the documentation Pub. 969 describes: enough to show the distribution went to qualified medical expenses, that the expense was not reimbursed from another source, and that it was not taken as an itemised deduction in any year.
Check the balance once more after the last claim posts. A pending claim is not a paid claim.
1 January – 15 March 2027
Only if your plan has a grace period
Two and a half months after a 31 December plan-year end lands on 15 March 2027. If your plan offers the grace period, expenses incurred through that date can still be reimbursed from the 2026 balance.
If your plan offers a carryover instead, this window does not exist for you — up to $680 of the 2026 balance rolls into 2027 and the rest is forfeited at the plan-year end.
File every claim by your plan's run-out deadline, which is set in your plan document and is a separate date from both of the above.
By April 15, 2027
HSA only — the deadline people miss in the other direction
Contributions for the 2026 tax year can be made until April 15, 2027. If you have room left and cash to fund it, you have months of runway that FSA holders do not.
Report the account on Form 8889 with your return.
Keep the receipts with your tax records — do not send them with the return.
Any time — for the rest of your life
The HSA's quiet superpower
There is no deadline to reimburse yourself from an HSA. A distribution can pay or reimburse an expense incurred in any prior year, as long as the expense post-dates the day the account was established and has not been reimbursed from another source or itemised on Schedule A.
That is the real reason to keep receipts, and the reason the retention clock runs from the return reporting the distribution rather than the year of the purchase. A 2026 receipt can still be the substantiation for a withdrawal twenty years from now.
There is no HSA-specific retention period anywhere in Pub. 969, Notice 2004-50 or §223. "Keep receipts forever" is practitioner advice — sound advice, but advice, not a rule.
The three tests, in one line
Whatever you are about to buy, it is being judged three separate ways at once — whether it is §213(d) medical care, whether the custodian’s claim desk waves it through, and whether it is deductible on Schedule A. They disagree constantly. The full category table scores all fifteen categories against all three.
Education only — not tax, legal or medical advice. Magellan does not decide what your plan will reimburse, and Magellan does not write, sign, sell, review or arrange Letters of Medical Necessity. Eligibility depends on your own plan documents and your own circumstances: confirm with your plan administrator before you spend, and take tax questions to a tax professional. Figures on this page come from the IRS documents cited beside them; they change, so check the citation.