What Is the Tax Liability for Employer HSA Contributions?

Employer contributions to an employee’s Health Savings Account are not subject to federal income tax, Social Security tax, or Medicare tax on the employee’s side, and the employer owes no payroll tax on them and can deduct them as a business expense. That tax-free treatment holds only while the employee qualifies as an eligible individual and total contributions from all sources stay within the annual cap. For 2026, the combined ceiling is $4,400 for self-only HDHP coverage and $8,750 for family coverage.¹ When either condition slips, the tax liability for employer HSA contributions can appear quickly, and it can fall on the employee, the employer, or both.

When the Contribution Stays Tax-Free

The exclusion rests on Internal Revenue Code Section 106(d), and it applies the same way whether the employer deposits money directly into the account or the employee routes pre-tax dollars through a Section 125 cafeteria plan. In either case the amount is left out of gross income and never flows into Social Security or Medicare wages.²³

To qualify, the employee must be covered by a High Deductible Health Plan and must have no disqualifying coverage. For 2026, an HDHP has to carry a minimum deductible of $1,700 for self-only coverage or $3,400 for family coverage, and out-of-pocket costs (deductibles, copays, and coinsurance, but not premiums) cannot exceed $8,500 or $17,000 respectively.¹

Several things disqualify an otherwise-covered employee: enrollment in Medicare, being claimed as a dependent on someone else’s return, or coverage under a general-purpose Flexible Spending Account or Health Reimbursement Arrangement. A limited-purpose FSA covering only dental and vision is fine.⁴

When the Contribution Becomes Taxable

If the employee is not an eligible individual when the money goes in, the contribution loses the Section 106(d) exclusion. It gets added to the employee’s taxable wages and becomes subject to federal income tax, Social Security, and Medicare taxes, exactly like regular pay.³

Excess Contributions

The exclusion only reaches the annual statutory limit. The 2026 cap of $4,400 (self-only) or $8,750 (family) covers everything combined: employer contributions, pre-tax employee contributions through a cafeteria plan, and any after-tax personal contributions. Employees aged 55 or older who are not enrolled in Medicare may add a $1,000 catch-up, a figure Congress did not index for inflation.⁵

Anything above the cap is an excess contribution. The employee must include the excess in gross income, and if it stays in the account at year-end it is hit with a 6% excise tax that repeats every year the excess remains.⁶

The 6% penalty can be avoided by withdrawing the excess plus any earnings on it before the tax-filing deadline, including extensions. An employee who already filed still has a window: pull the excess within six months of the unextended due date and file an amended return with “Filed pursuant to section 301.9100-2” at the top. Earnings withdrawn with the excess get reported as other income.⁶

Failing the Last-Month Rule Testing Period

Normally the contribution limit is prorated month by month. The last-month rule lets an employee who is eligible on December 1 contribute the full annual limit for the year, even if HDHP coverage started partway through. The condition is a testing period: the employee has to stay eligible through December 31 of the following year.³

If eligibility is lost during the testing period for any reason other than death or disability, the amount contributed above the month-by-month limit gets added back to income and carries a 10% additional tax. Switching to non-HDHP coverage mid-year or signing up for Medicare are common triggers. The hit is largest when an employer front-loaded a big contribution on the assumption of full-year eligibility.³

Employer-Side Tax Treatment

Qualified employer HSA contributions are exempt from the employer’s share of FICA, which is Social Security at 6.2% and Medicare at 1.45%, a 7.65% savings on every dollar contributed.⁷⁸⁹ The contributions are also deductible as an ordinary business expense, just like salary, so the employer lowers both payroll tax and taxable income on the same dollar.

Comparability Penalty

An employer who contributes outside a cafeteria plan has to follow the comparability rules. Comparable participating employees in the same coverage category must receive either the same dollar amount or the same percentage of the HDHP deductible. Self-only and family coverage are tested separately, and the amounts across those tiers do not have to match.¹⁰

Breaking the rules triggers a 35% excise tax on the total the employer contributed to all employee HSAs for the period. The penalty falls on the employer only. Contributions routed through a cafeteria plan are not subject to comparability testing because Section 125 nondiscrimination rules apply instead.¹¹

How the Numbers Should Appear on Your W-2

Every employer HSA contribution, including pre-tax amounts the employee elected through a cafeteria plan, is reported on Form W-2 in Box 12 with Code W. The figure is informational and must not be included in Box 1, Box 3, or Box 5 wages.¹²

The Code W amount flows to Line 9 of Form 8889, which every HSA holder files with their return. Cafeteria plan contributions are treated as employer contributions on that form, so they should not be entered again on Line 2, which is for after-tax personal contributions. If employer contributions straddle two calendar years, the Employer Contribution Worksheet in the Form 8889 instructions allocates the right amount to each tax year.⁶

If the employer accidentally rolls qualified HSA contributions into the taxable wage boxes, the right response is to ask for a corrected W-2. Absent a correction, the IRS reads those amounts as wages, and the employee ends up overpaying.⁶

State Tax Exceptions

The federal exclusion does not automatically carry over to the states. California and New Jersey do not conform. In those states, both employer and employee HSA contributions made through payroll are treated as taxable income for state purposes, and investment growth inside the account is taxed at the state level as well. Residents still receive the full federal benefit but should plan on a state tax bill that employees elsewhere do not face.

2026 Expansions That Bring More Employees Into Eligibility

The One, Big, Beautiful Bill Act widened HSA eligibility starting January 1, 2026, which in turn widens the group of employees who can receive tax-free employer contributions:¹³

Marketplace bronze and catastrophic plans are now treated as HDHPs even if they fall outside the traditional minimum-deductible or maximum-out-of-pocket thresholds. Most bronze plans previously could not support HSA contributions because their out-of-pocket limits exceeded HDHP ceilings.
Enrollment in a direct primary care service arrangement no longer disqualifies an employee, and HSA funds can be used tax-free to pay periodic direct primary care fees.
The telehealth safe harbor is permanent. HDHPs can cover telehealth and remote care services before the deductible is met without jeopardizing HSA eligibility, retroactive to plan years beginning after December 31, 2024.

Employers offering bronze marketplace coverage should check whether workers who were ineligible last year can now receive tax-free HSA contributions.⁴

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
Internal Revenue Service. HSA Limits on Contributions
6
Internal Revenue Service. Instructions for Form 8889
7
Social Security Administration. Social Security and Medicare Tax Rates
8
Internal Revenue Service. FUTA Credit Reduction
9
Employment and Training Administration. UIPL 15-04 Wages – Treatment of Health Savings Accounts
10
Office of the Law Revision Counsel. 26 USC 4980G – Failure of Employer to Make Comparable Health Savings Account Contributions
11
U.S. Department of the Treasury. Employer Comparable Contributions to Health Savings Accounts
12
Internal Revenue Service. Form W-2 Reporting of Employer-Sponsored Health Coverage
13
Internal Revenue Service. Treasury, IRS Provide Guidance on New Tax Benefits for Health Savings Account Participants Under the One, Big, Beautiful Bill