Updated October 16, 2026. Quick answer: The 2025 Form 8889 instructions count contributions for a year up to the unextended deadline for filing that year’s return. Applied to 2026, that is April 15, 2027, a Thursday, which is computed here and not published by the IRS. The 2026 limits are $4,400 for self-only coverage and $8,750 for family coverage, and an extension of time to file does not extend the contribution date.
IRS worksheets read line by line: Form 8889 Line 3 Limitation Worksheet.
Related reading on this site: IRS Publication 969.
Form 8606 and Form 8889 for 2025, read line by line: Form 8889 lines 3, 4 and 5, Form 8889 lines 6, 7 and 8 and Form 8889 lines 9 to 13.
More IRS forms and schedules, read line by line: Form 4868 extension.
The deadline for tax year 2026
The Form 8889 instructions, line 2, explain which contributions count for a year: “Also, include amounts contributed for 2025 made in 2026 by the unextended deadline for filing your 2025 federal income tax return, April 15, 2026.” “Thus, you may contribute to your 2025 HSA through April 15, 2026, or a later date if you served in a designated combat zone or contingency operation.”
Publication 969 says the same under the heading When To Contribute: “You can make contributions to your HSA for 2025 through April 15, 2026.”
Moving that wording forward one year, the HSA deadline for tax year 2026 is April 15, 2027. April 15, 2027 falls on a Thursday (computed here, not published by the IRS).
| Year | Deadline | What the source says |
|---|---|---|
| Tax year 2025 | April 15, 2026 (past as of October 16, 2026) | “You can make contributions to your HSA for 2025 through April 15, 2026.” |
| Tax year 2026 | April 15, 2027, a Thursday (computed here, not published by the IRS) | Same wording moved forward one year: the unextended deadline for filing the 2026 return |
Why the extension does not help
The instructions use the word that matters: the deadline is “the unextended deadline for filing your 2025 federal income tax return”. Filing an extension for the return moves the filing date, but the wording above ties the contribution date to the unextended deadline. The one carve-out the instructions print is military: “If you were serving in, or in support of, the U.S. Armed Forces in a designated combat zone or contingency operation, you may be able to file later.”
An employer-side wrinkle works the same way for the calendar. The publication says “Your employer can make contributions to your HSA from January 1, 2026, through April 15, 2026, that are allocated to 2025.” “Your employer must notify you and the trustee of your HSA that the contribution is for 2025.” Shifted one year, employer money received between January 1 and April 15, 2027 can be allocated to 2026 when that notice is given.
The 2026 limits
The publication’s tip box prints both 2026 figures: “For 2026, if you have self-only HDHP coverage, you can contribute up to $4,400.” “If you have family HDHP coverage, you can contribute up to $8,750.” The Revenue Procedure prints the same amounts as the annual limitation on deductions.
| 2026 coverage | Publication 969 | Revenue Procedure 2025-19 |
|---|---|---|
| Self-only HDHP coverage | “you can contribute up to $4,400.” | “deductible health plan is $4,400.” |
| Family HDHP coverage | “you can contribute up to $8,750.” | “deductible health plan is $8,750.” |
The maximum is not simply a gift from the plan year. The Form 8889 instructions say: “Your maximum contribution is reduced by any employer contributions to your HSA, any contributions made to your Archer MSA, and any qualified HSA funding distributions.” Employer money, including payroll contributions through a cafeteria plan, counts toward the limit. For the full 2026 limit rules see the 2026 HSA contribution limits page.
The age 55 and older catch-up
Publication 969 prints the additional amount for older savers: “If you are an eligible individual who is age 55 or older at the end of your tax year, your contribution limit is increased by $1,000.” That sentence is in the edition written for 2025 returns. Read the amount again in the 2026 version of the Form 8889 instructions before relying on it for a 2026 contribution. Couples with two eligible spouses should read the HSA catch-up for both spouses page.
The last-month rule and the testing period
A person who becomes eligible late in the year can still reach the full limit. The instructions say: “if you are an eligible individual on the 1st day of the last month of the tax year (December 1, for most individuals).” “The testing period begins with the last month of your tax year and ends on the last day of the 12th month following that month”
There is a price for failing the testing period: “If you fail to remain an eligible individual during this period, other than because of death or becoming disabled, you will have to include in income the total contributions made that would not have been made except for the last-month rule.” “This amount is also subject to a 10% additional tax.”
Reporting on Form 8889
Contributions for the year are reported on the form: “Report all contributions to your HSA on Form 8889 and file it with your Form 1040, 1040-SR, or 1040-NR.” “You should include all contributions made for 2025, including those made from January 1, 2026, through April 15, 2026, that are designated for 2025.”
Moved forward one year, that includes money contributed between January 1 and April 15, 2027 and designated for 2026. The line-by-line walk is on the Form 8889 page, and mistakes in the amount are handled on the HSA excess contribution fix page.
The editions read for this page are IRS Publication 969 (for use with 2025 returns), the 2025 Instructions for Form 8889 and Revenue Procedure 2025-19 for the 2026 amounts, which are the revisions irs.gov served when they were read on 2026-10-16. The publication and form instructions speak of tax year 2025, so the 2026 dates on this page are the same wording moved forward one year, computed here. Check the revision of the instructions for the form you are filing.
Common mistakes
- Waiting for an extension to contribute. The Form 8889 instructions count contributions made by the unextended deadline for filing the return, so an extension of time to file does not add days.
- Dropping out of an HDHP after using the last-month rule. The instructions say that failing to remain an eligible individual during the testing period means including the extra contributions in income, plus a 10% additional tax.
- Counting only your own deposits against the limit. The instructions say the maximum contribution is reduced by employer contributions, so payroll deposits through a cafeteria plan use up room.
Related: 2026 HSA contribution limits, Form 8889 instructions, HSA excess contribution fix, HSA catch-up for both spouses, and HSA priority order.
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Answer againSources
- IRS Publication 969, Health Savings Accounts and Other Tax-Favored Health Plans, for 2025 returns: https://www.irs.gov/pub/irs-pdf/p969.pdf
- 2025 Instructions for Form 8889, Health Savings Accounts (HSAs): https://www.irs.gov/pub/irs-pdf/i8889.pdf
- IRS Rev. Proc. 2025-19 (2026 inflation adjusted HSA amounts): https://www.irs.gov/pub/irs-drop/rp-25-19.pdf
Read from the IRS documents linked above on October 16, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.