What Is the Tax Liability for Employer HSA Contributions?

Employer contributions to a Health Savings Account are excluded from the employee’s gross income and exempt from federal income tax, Social Security, and Medicare tax, and the employer can deduct them as a business expense while avoiding its share of payroll taxes on the amount. The tax on employer HSA contributions is effectively zero on both sides, but only when the employee qualifies as an eligible individual and total contributions from all sources stay within the annual cap. For 2026, that cap is $4,400 for self-only HDHP coverage and $8,750 for family coverage.¹ Miss either condition and the money becomes taxable, sometimes with penalties on top.

What the Employee Pays (and Doesn’t Pay)

Under Internal Revenue Code Section 106(d), an employer’s HSA contribution to an eligible employee is excluded from gross income.² The exclusion covers federal income tax, Social Security tax, and Medicare tax. It applies whether the employer deposits the money directly or the employee funds the account through pre-tax payroll deductions in a Section 125 cafeteria plan.³

The exclusion collapses the moment the employee stops being an eligible individual. If eligibility fails at the time of the contribution, the amount is added to taxable wages and taxed like any other pay.³ Eligibility means:

Enrollment in a High Deductible Health Plan. For 2026, minimum deductibles are $1,700 self-only and $3,400 family, with out-of-pocket maximums of $8,500 and $17,000.¹
No enrollment in Medicare.
Not being claimed as a dependent on someone else’s return.
No disqualifying secondary coverage. A general-purpose FSA or HRA disqualifies; a limited-purpose FSA covering only dental and vision does not.⁴

What the Employer Pays (and Deducts)

Qualified employer HSA contributions are exempt from the employer’s share of FICA, which is 6.2% Social Security plus 1.45% Medicare, a saving of 7.65% on every dollar contributed.⁵⁶ The employer also deducts the contribution as an ordinary business expense, the same treatment given to wages. Lower payroll taxes plus a business deduction is the reason employer HSA funding is often cheaper than an equivalent raise.

Annual Contribution Limits and the Cost of Going Over

The tax exclusion only reaches contributions up to the statutory annual limit. For 2026, that’s $4,400 for self-only HDHP coverage and $8,750 for family coverage, and the ceiling is aggregate: employer contributions, employee pre-tax cafeteria-plan contributions, and any after-tax deposits all count against the same number.¹ Employees aged 55 or older who are not on Medicare can add a $1,000 catch-up contribution, an amount fixed by statute and not indexed for inflation.⁷

Anything above the limit is an excess contribution. It must be included in the employee’s gross income, and it draws a 6% excise tax for every year it remains in the account. Withdrawing the excess plus any earnings before the tax-filing deadline (including extensions) avoids the excise tax; earnings pulled out with it get reported as other income for that year.⁸

Comparability Rules for Contributions Outside a Cafeteria Plan

An employer contributing to employee HSAs outside a Section 125 cafeteria plan must make comparable contributions to all comparable participating employees: the same dollar amount or the same percentage of the HDHP deductible within each coverage category. Self-only and family coverage are tested separately, so the amounts can differ across those tiers.⁹

A violation triggers a 35% excise tax on the total amount the employer contributed to all employee HSAs during that period.¹⁰ The penalty is the employer’s alone. Contributions run through a cafeteria plan escape comparability testing because the Section 125 nondiscrimination rules apply instead.

The Last-Month Rule and Its Testing Period

Ordinarily, the annual limit is prorated by the months of eligibility. The last-month rule is a shortcut: an eligible individual on December 1 is treated as eligible for the full year and can contribute the full annual limit.³

The condition is a testing period that runs through December 31 of the following year. Lose eligibility during that window for any reason other than death or disability, and the amount contributed above the month-by-month limit is added back to income and hit with an additional 10% tax.³ Employees who switch to non-HDHP coverage mid-year or enroll in Medicare are the common cases. A large front-loaded employer contribution makes the fallout larger.

W-2 and Form 8889 Reporting

Employer HSA contributions appear on Form W-2 in Box 12 with Code W. Direct employer contributions and employee pre-tax cafeteria-plan contributions both go there. The Code W amount is informational; it is not included in the taxable wages reported in Box 1, Box 3, or Box 5.¹¹

The employee reports the Box 12 Code W total on Line 9 of Form 8889. Cafeteria-plan contributions are treated as employer contributions there, so don’t also enter them on Line 2, which is only for personal after-tax contributions. If a contribution for one tax year is actually deposited in the following year, use the Employer Contribution Worksheet in the Form 8889 instructions to allocate it correctly.⁸

If a qualified contribution ends up in the taxable wage boxes by mistake, ask for a corrected W-2. Without it, the IRS reads the amount as taxable pay and the employee ends up overpaying.⁸

Deadline for Contributions

Employer contributions for a given tax year can be deposited any time from January 1 of that year through the following April tax-filing deadline. Contributions for 2026 can land as late as April 15, 2027, and still count against the 2026 limit.³ Payroll-cycle funding, a year-end lump sum, or an early-following-year deposit all work, as long as the deadline is met.

Expanded Eligibility Starting in 2026

The One, Big, Beautiful Bill Act broadened HSA eligibility effective January 1, 2026, which widens the pool of employees who can receive tax-free employer contributions:¹²

Marketplace bronze and catastrophic plans are now treated as HDHPs even if they fall outside the traditional minimum-deductible or maximum-out-of-pocket limits. This opens HSAs to employees whose bronze coverage previously disqualified them.
Enrolling in a direct primary care service arrangement no longer breaks eligibility, and HSA funds can pay periodic direct primary care fees tax-free.
Coverage of telehealth and remote care before the deductible is met, once a temporary pandemic measure, is now a permanent feature of HDHPs, retroactive to plan years beginning after December 31, 2024.

Employers offering bronze marketplace plans should check whether workers who were previously ineligible now qualify.⁴

State Tax Treatment Is Not Universal

The federal exclusion does not automatically apply for state income tax. California and New Jersey do not conform to the federal HSA rules. In those states, employer and employee HSA contributions made through payroll are taxable for state purposes, and account earnings are also taxed at the state level. The federal treatment described above is unaffected.

1
Internal Revenue Service. Rev. Proc. 2025-19
2
GovInfo. 26 USC 106 – Contributions by Employer to Accident and Health Plans
3
Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans
4
Internal Revenue Service. Notice 2026-05 – Expanded Availability of Health Savings Accounts under the One, Big, Beautiful Bill Act
5
Social Security Administration. Social Security and Medicare Tax Rates
6
Employment and Training Administration. UIPL 15-04 Wages – Treatment of Health Savings Accounts
7
Internal Revenue Service. HSA Limits on Contributions
8
Internal Revenue Service. Instructions for Form 8889
9
Office of the Law Revision Counsel. 26 USC 4980G – Failure of Employer to Make Comparable Health Savings Account Contributions
10
U.S. Department of the Treasury. Employer Comparable Contributions to Health Savings Accounts
11
Internal Revenue Service. Form W-2 Reporting of Employer-Sponsored Health Coverage
12
Internal Revenue Service. Treasury, IRS Provide Guidance on New Tax Benefits for Health Savings Account Participants Under the One, Big, Beautiful Bill