The FSA Deadline: When Your Money Expires, the Grace Period and Carryover Rules, and the Lab Tests That Use a Balance Before It's Gone

Health flexible spending accounts are funded through your employer's plan year, and for most plans that year is the calendar year, so the deadline is December 31. What you have not spent by then is gone — unless your plan adopted one of the two exceptions the IRS allows. A grace period gives you until March 15 to incur new expenses against last year's balance. A carryover rolls up to $680 of unused 2026 money into next year, with anything above that forfeited. A plan may offer one, the other, or neither, and that detail sits in your plan documents or HR portal, not on the card. Two things make lab testing a clean way to use a balance: blood tests are a qualified medical expense under IRS Publication 502 whoever ordered them, and the expense date is the day of the draw, so you can order in late December, be drawn before the year ends and let the results post in January.

Two more dates matter. Most plans have a run-out period, often 90 days after the plan year, to file claims for expenses already incurred — keep the receipt. And the 2026 health FSA contribution limit is $3,400 (Rev. Proc. 2025-32), which is the most you could have at stake. HSAs are different: no deadline at all, the balance is yours indefinitely, and 2026 limits are $4,400 self-only / $8,750 family plus $1,000 at 55 or older (Rev. Proc. 2025-19).

FSA rules care about when a medical service is provided. For a lab test that is the day the sample is taken — not the day you order, and not the day the result posts. A December 29 order drawn on December 30 belongs to 2026 even if the report lands on January 2; the same order drawn on January 3 belongs to 2027 unless you have a grace period. Through TestWell the physician authorization usually arrives within minutes of checkout and most Quest and Labcorp patient service centers take walk-ins, so there is no scheduling gap to plan around — but the lab finder and location pages show hours, and draw sites run reduced schedules around the holidays. Aim to be drawn by December 30 rather than betting on the 31st.

Spend it on the tests you'd want anyway — a leftover balance is a reason to stop postponing, not a reason to over-test. Sensible December patterns, by balance (TestWell prices; one $6 fee per order covers the physician authorization):

• Under $50: one test you've been meaning to check — a hemoglobin A1c ($21.99) if you have a family history of diabetes, a vitamin D ($41.99) before winter, a TSH ($26.99) if you've had thyroid symptoms, or a ferritin ($24.99) for unexplained fatigue.
• $50–$200: the annual baseline. The General Wellness Panel ($49.99) covers the four tests a physical orders (CMP, CBC with differential, lipid panel, TSH); the Essential Health Panel ($189.99) adds A1c, vitamin D, iron and inflammation markers.
• $200+: the baseline plus the follow-ups your history suggests — the Heart Health Panel ($99.99; ApoB, Lp(a), hs-CRP with the lipid panel and A1c) if heart disease runs in the family, hormone panels, or the General Wellness Advanced Panel ($209.99) for a 14-test picture.
• Requirements with a January deadline: a TB blood test ($91.99) or immunity titers for school, clinical programs or a new job — cash-pay, HSA/FSA eligible, results in days.

The end-of-year blood work checklist turns this into an order-by calendar with fasting notes and turnaround times.

Two ways, and neither needs a special form. Pay with the FSA card at checkout — it runs as an ordinary card, and TestWell is coded as a medical provider so most cards approve without a substantiation request. Or pay another way and submit the receipt: every order produces an itemized receipt in your account showing the provider, the date of service, each test by name, the $6 lab processing fee, the total paid and the last four digits of the card — the fields substantiation asks for. Lab results are never needed for a claim. If your administrator classifies a wellness panel as general screening and asks for more, a short letter of medical necessity from your clinician settles it. The FSA and HSA guide covers eligibility in more detail.