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Form 8889 Calculator

Compute your IRS Form 8889 Health Savings Account (HSA) deduction (Line 13), mid-year pro-rata vs. Last-Month Rule limit ($4,400 self-only or $8,750 family in 2026, plus $1,000 catch-up at age 55+), and any 20% non-qualified distribution penalty (Line 17b) or 10% testing-period penalty (Line 21).

Updated November 7, 2026. Free, no sign-up; everything runs in your browser and nothing you type is stored.

IRS Form 8889 line-by-line HSA calculator (2026)

HDHP coverage tier Your age at year-end Months HDHP-eligible (1–12) Use Last-Month Rule (eligible Dec 1)?

Employer + payroll W-2 Box 12 (Code W) ($) Your direct post-tax HSA contributions ($) Total HSA distributions taken (Line 14a) ($) Qualified medical expenses paid (Line 15) ($)

Combined federal + state marginal tax rate (%)

Form 8889 Line 3 maximum allowed HSA contribution

–

–Line 13 above-the-line deduction

–Total tax + FICA savings

–Excess contribution (Form 5329 6% tax)

–Line 17b 20% penalty + income tax

2026 & 2027 HSA Contribution Limits on IRS Form 8889 (Rev. Proc. 2025-19)

HSA statutory parameter	2025 tax year	2026 tax year
Self-only HDHP maximum contribution (Line 3)	$4,300	$4,400
Family HDHP maximum contribution (Line 3)	$8,550	$8,750
Age 55+ catch-up contribution (Line 7)	$1,000	$1,000
Minimum HDHP deductible (Self / Family)	$1,650 / $3,300	$1,700 / $3,400
Maximum HDHP out-of-pocket cap (Self / Family)	$8,300 / $16,600	$8,500 / $17,000

How Form 8889 Parts I, II and III work

Part I (Lines 1–13) computes your maximum annual contribution based on the number of months you held qualifying High Deductible Health Plan (HDHP) coverage on the 1st day of the month. Employer contributions and pre-tax cafeteria-plan payroll deferrals (W-2 Box 12, Code W) go on Line 9 and are already excluded from federal income and 7.65% FICA taxes; your direct post-tax contributions go on Line 2 and produce an above-the-line deduction on Line 13 (Schedule 1, Line 13). Part II (Lines 14a–17b) compares total distributions against unreimbursed qualified medical expenses: any non-qualified withdrawal is taxed as ordinary income on Line 16 plus a 20% additional tax on Line 17b (waived after age 65, disability, or death). Part III (Lines 18–21) applies a 10% penalty plus income tax if you used the December 1 Last-Month Rule to contribute the full annual limit mid-year but failed to remain HDHP-eligible through December 31 of the following testing year.

Form 8889 HSA Calculator Worked Example: W-2 Code W & Line 13 Deduction

In 2026, a 42-year-old with 12 months of family HDHP coverage has a $8,750 limit on Form 8889 Line 3. Their employer contributes $1,500 via W-2 Code W (Line 9), leaving $7,250 of remaining room (Line 12). Contributing $7,250 directly (Line 2) yields a $7,250 above-the-line deduction on Line 13. At a 24% marginal tax rate, total tax savings equal $1,740 on direct contributions plus $474.75 on the $1,500 payroll deferral (24% + 7.65% FICA) = $2,214.75 saved. Because all $1,200 of distributions matched $1,200 of medical expenses, Line 16 taxable distributions and Line 17b penalty are $0.

Common questions

Where do W-2 Box 12 Code W contributions go on Form 8889?

All employer HSA contributions and pre-tax employee payroll deductions reported in Box 12 of Form W-2 with Code W are entered on Form 8889, Line 9. Do not enter them on Line 2, or you will double-count a deduction already excluded from your W-2 Box 1 wages.

How does the Form 8889 mid-year pro-rata rule work?

Under the IRS sum-of-monthly-limits rule, you count each month you had qualifying HDHP coverage on the 1st of the month and divide by 12. For example, 6 months of 2026 family coverage without the Last-Month Rule allows 6/12 × $8,750 = $4,375.

What is the penalty for a non-qualified HSA withdrawal on Form 8889?

Any distribution on Line 14a that exceeds your unreimbursed qualified medical expenses on Line 15 is added to your taxable income on Line 16 and hit with a 20% additional tax on Line 17b, unless you are age 65 or older, disabled, or deceased.

Sources

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General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.