How to Complete Form 8889 Part 1: Contributions, Limits, and Deduction

Part I of Form 8889 is where you calculate your Health Savings Account deduction, and to complete Form 8889 Part I you work down the page in order: confirm your HDHP coverage type, add up your personal contributions, figure your contribution limit for the year, subtract what your employer put in, and take the smaller of your contributions or what remains. For 2026, the annual limit is $4,400 for self-only HDHP coverage or $8,750 for family coverage, plus an extra $1,000 if you’re 55 or older by year-end.¹ Errors here cost real money: a missed deduction reduces your refund, and an unreported excess contribution triggers a 6% excise tax that compounds every year the money stays in the account.

Confirm You’re Eligible Before You Start

Part I only produces a valid deduction if you were an eligible individual for at least one month. The core test: you’re covered by a qualifying High Deductible Health Plan, you’re not enrolled in Medicare, no one can claim you as a dependent, and you have no disqualifying secondary coverage such as a general-purpose health FSA or HRA.²

For 2026, an HDHP must carry a minimum annual deductible of at least $1,700 (self-only) or $3,400 (family), with an out-of-pocket maximum no higher than $8,500 or $17,000 respectively.³ Beginning in 2026, bronze-level and catastrophic Marketplace plans also count as HDHPs regardless of whether they meet those thresholds, and this treatment applies even when the plan was purchased off-Exchange.⁴

Eligibility is decided month by month, based on your status on the first day of each month.² That monthly tracking drives the Line 3 proration below.

The disqualifier that catches the most people is a general-purpose health FSA or HRA. If you or your spouse signed up for one during open enrollment, you’re ineligible for HSA contributions during any month that coverage is in force. A limited-purpose FSA (dental, vision, preventive care only), a post-deductible FSA or HRA, or a suspended HRA does not disqualify you. Watch the FSA grace period too: if you carried a balance from a prior plan year into a general-purpose FSA grace period, those months are disqualified unless your balance was zero at year-end.⁵

Line 1: Self-Only or Family Coverage

Check the box that matches your HDHP coverage. If you had family HDHP coverage at any point in the year, use family and disregard any self-only plan you also had. The same rule applies if your spouse’s family HDHP included you.⁶ This selection sets the ceiling used everywhere below.

Line 2: Your Own Contributions

Enter contributions you personally made to your HSA for the tax year, including any you make between January 1 and the April filing deadline that you designate for the prior year.⁶ Do not include:

Employer contributions or anything you funded through a cafeteria plan payroll deduction (those go on Line 9).
Rollovers from another HSA or Archer MSA.
A qualified HSA funding distribution from an IRA (that goes on Line 10).⁶

Your HSA custodian’s Form 5498-SA is the cleanest reconciliation. Box 2 shows contributions received during the calendar year, and Box 3 shows contributions made in the following year but designated for the prior year.⁷ Form 5498-SA typically arrives after tax season opens, so early filers may need to rely on personal records first.

Line 3: Your Contribution Limit

Line 3 is where most of the math lives. What you enter depends on how many months you were eligible and whether you’re using the last-month rule.

Eligible All Twelve Months

If you were an eligible individual every month of the year with the same coverage type, enter the full annual limit: $4,400 (self-only) or $8,750 (family) for 2026.¹

Eligible for Only Part of the Year

Divide the annual limit by twelve, then multiply by the number of qualifying months. Self-only coverage for seven months of 2026 works out to $4,400 ÷ 12 × 7 = $2,567 (rounded). The Form 8889 instructions include a Line 3 Limitation Chart and Worksheet for handling coverage changes or a mix of self-only and family months.⁶

Last-Month Rule

If you were an eligible individual on December 1 of the tax year, you may contribute the full annual limit for that year even if you were eligible for only part of it. Someone who first enrolled in an HDHP in October can still contribute the full $4,400 or $8,750.⁵

The rule comes with a testing period: you must remain an eligible individual from December 1 of the tax year through December 31 of the following year. Fail it (drop the HDHP, start Medicare, pick up a disqualifying FSA), and the amount you couldn’t have contributed under normal proration gets added to your income for the failure year, plus a 10% additional tax. Death and disability are the only exceptions.⁸⁵

Catch-Up If You’re 55 or Older

Turning 55 by December 31 buys you an extra $1,000. This amount is fixed by statute and does not adjust for inflation.⁹ Where you enter it depends on filing status: unmarried filers, or married filers with self-only coverage all year, add the $1,000 into Line 3. Married filers with family coverage at any point during the year enter the $1,000 on Line 7 instead.

Spouses cannot pool a catch-up. If both of you are 55 or older, each needs a separate HSA and a separate Form 8889 to claim the extra $1,000.⁶

Lines 9 Through 12: What Your Employer Contributed and What’s Left

Line 9 captures employer contributions and anything you funded through a Section 125 cafeteria plan payroll deduction. The figure appears in Box 12 of your W-2 with Code W.⁶ Those dollars were already excluded from your taxable wages, so they don’t get deducted twice; their function on the form is to reduce the room you have left.

Line 10 is for a qualified HSA funding distribution, a one-time, tax-free transfer from a traditional or Roth IRA to your HSA. The maximum is your annual contribution limit, and the election is generally once in a lifetime unless you move from self-only to family coverage. The transferred amount consumes contribution room but isn’t deductible.⁶

Line 12 subtracts Lines 9 through 11 from your Line 3 limit (or Line 6 if you had to split a family limit with a spouse, plus any Line 7 catch-up). What’s left is the ceiling on your personal deduction.

Line 13: The Deduction

Enter the smaller of your Line 2 contributions or your Line 12 remaining limit. That figure is your HSA deduction, and it moves to Line 13 of Schedule 1 (Form 1040), reducing your adjusted gross income.⁶ Because it’s above the line, you get the benefit whether you itemize or take the standard deduction.¹⁰

If You Contributed Too Much

Subtract Line 13 from Line 2. Any positive difference is an excess contribution. It’s not deductible, and a 6% excise tax reported on Form 5329 applies for the year of the excess and each following year the money remains in the account.⁸⁵

You can avoid the penalty by withdrawing the excess plus any earnings on it before your filing deadline including extensions. The earnings are taxable income in the year of withdrawal, and you cannot deduct the withdrawn contributions.⁸ Miss the deadline and the excess can be absorbed in a future year with unused room, but the 6% tax runs each year until it’s gone.

A State-Level Boundary

The deduction you calculate on Form 8889 applies to your federal return. A small number of states do not follow the federal treatment, and residents there owe state tax on HSA contributions, earnings, and employer contributions even though the money is federally tax-free. Payroll HSA contributions still reduce federal wages on your W-2, but you’d add them back on the state return. Check your state’s income tax instructions before assuming the full federal benefit flows through.

File the Form Even in Quiet Years

Form 8889 must be attached to Form 1040, 1040-SR, or 1040-NR whenever you had an HSA during the year, whether you contributed, took distributions, or did neither.⁶ Part I is where the deduction lives; skipping it leaves money on the table, and an unreported excess quietly accrues 6% a year until someone catches it.

1
Internal Revenue Service. IRS Notice 2026-05 – Expanded Availability of Health Savings Accounts Under the OBBBA
2
Internal Revenue Service. Individuals Who Qualify for an HSA
3
Internal Revenue Service. Revenue Procedure 2025-19
4
Internal Revenue Service. Treasury, IRS Provide Guidance on New Tax Benefits for Health Savings Account Participants Under the One, Big, Beautiful Bill
5
Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans
6
Internal Revenue Service. 2025 Instructions for Form 8889
7
Internal Revenue Service. Instructions for Forms 1099-SA and 5498-SA
8
Internal Revenue Service. Instructions for Form 8889 (2025)
9
Internal Revenue Service. HSA Contribution Limits
10
Internal Revenue Service. 2025 Schedule 1 (Form 1040)