To set up an HSA for a small business, you offer employees a health plan that meets the IRS definition of a High Deductible Health Plan, choose a bank or administrator to hold the accounts, and then run employee and employer contributions through payroll on a pre-tax basis. There is no minimum company size. For 2026, the combined annual contribution limit is $4,400 for self-only HDHP coverage and $8,750 for family coverage, with employees aged 55 or older allowed an extra $1,000.1Internal Revenue Service. Rev. Proc. 2025-19 Done right, the account carries a rare triple tax advantage: contributions reduce taxable income, growth inside the account is tax-free, and withdrawals for qualified medical expenses are tax-free too.
Step 1: Offer a Qualifying High Deductible Health Plan
Everything else depends on this. If the group health plan does not meet IRS thresholds, no one can contribute to an HSA. For 2026, the plan must have:
- Self-only coverage: a deductible of at least $1,700 and an out-of-pocket maximum no higher than $8,500 (deductibles, copays, and coinsurance count toward that cap; premiums do not).
- Family coverage: a deductible of at least $3,400 and an out-of-pocket maximum no higher than $17,000.
These figures are set in Rev. Proc. 2025-19 and change each year with inflation.1Internal Revenue Service. Rev. Proc. 2025-19 When you talk to a broker, say upfront that you need an HSA-compatible HDHP. Most major insurers carry at least one such plan, but ask for plan documents that explicitly confirm HDHP status. A plan with a high deductible can still disqualify employees if it pays for services before the deductible is met beyond what the IRS allows for preventive care.
Step 2: Choose an HSA Custodian
HSA funds must sit with a qualified custodian, typically a bank, credit union, insurance company, or specialized HSA administrator. The custodian opens and holds each employee’s individual account. When comparing options, three things matter most:
- Fees. Monthly account maintenance fees, investment fees, and charges for debit cards or paper statements add up across a workforce.
- Investment options. Some custodians offer only an interest-bearing cash account; others open mutual funds or other investments once a balance threshold is met. Employees treating the HSA as long-term savings will care.
- Payroll integration. The custodian should accept electronic contribution files in a format your payroll system can produce. Manual processing invites errors.
Once you pick a custodian, you sign a service agreement that spells out your role in sending contributions and the custodian’s role in administering accounts and handling tax reporting. You provide your Employer Identification Number and company contact information to establish the employer relationship; the custodian handles the individual account setup for each enrolled employee.
Step 3: Confirm Who’s Eligible to Contribute
Not every employee on your HDHP will qualify. Eligibility is checked month by month. On the first day of each month, an employee must:
- Be enrolled in your qualified HDHP.
- Have no disqualifying coverage, such as a spouse’s traditional low-deductible plan or a general-purpose Flexible Spending Account.
- Not be enrolled in any part of Medicare.
- Not be claimed as a dependent on someone else’s tax return.
These rules apply regardless of company size.2Internal Revenue Service. Individuals Who Qualify for an HSA You are not expected to audit a spouse’s coverage, but you should ask employees to certify their eligibility at enrollment. If someone loses HDHP coverage or picks up disqualifying coverage during the year, stop their contributions right away.
One coordination point if you already offer an FSA: a general-purpose FSA kills HSA eligibility, but a limited-purpose FSA covering only dental and vision does not. Converting an existing FSA to a limited-purpose version lets employees use both accounts side by side. The 2026 limited-purpose FSA contribution limit is $3,400.
Step 4: Set the Contribution Structure
Employer and employee contributions share one annual cap. For 2026 that cap is $4,400 for self-only HDHP coverage and $8,750 for family coverage, plus a $1,000 catch-up for employees 55 and older.3Internal Revenue Service. HSA Contribution Limits
You have broad flexibility on the employer side. You can contribute a flat dollar amount per employee, match employee contributions up to a limit, or make no employer contribution at all. Employer contributions are deductible as a business expense and are excluded from the employee’s gross income. Many small businesses add a modest employer contribution to soften the higher deductible that comes with an HDHP, since that is the most common objection when switching plans.
Payroll deductions for employee contributions come out before federal income tax, Social Security tax, and Medicare tax. The FICA piece is distinctive. Unlike a traditional IRA deduction, HSA payroll contributions cut both the employee’s and the employer’s FICA liability. An employee earning $60,000 who contributes $4,400 saves roughly $337 in FICA, and the employer saves the same amount.4Voya. The Undervalued Benefit of HSA Programs Employers and Employees May Be Missing: FICA Savings That only works if the deduction is coded as pre-tax in payroll. Post-tax coding costs both sides the FICA savings and forces the employee to claim the deduction on their personal return.
Step 5: Follow the Comparability Rule (or Use a Cafeteria Plan)
This is the costliest trap in small-business HSA administration. If you contribute to employee HSAs outside of a cafeteria plan, the IRS comparability rule requires that employer contributions be the same dollar amount, or the same percentage of the HDHP deductible, for every eligible employee in the same coverage category. Self-only and family coverage are tested separately, so the two tiers can get different amounts, but within a tier everyone must get the same deal.5eCFR. 26 CFR 54.4980G-4 – Calculating Comparable Contributions
Breaking the rule triggers a 35% excise tax on every dollar the employer contributed to all employee HSAs that calendar year, not just the unequal portion.6Office of the Law Revision Counsel. 26 U.S. Code 4980G – Failure of Employer to Make Comparable Health Savings Account Contributions
Two safe approaches:
- Keep it simple. Contribute one flat dollar amount for each employee in each coverage tier.
- Route contributions through a Section 125 cafeteria plan. Comparability does not apply when HSA contributions flow through a cafeteria plan, which lets you offer matching, salary-tiered, or class-based employer contributions. The trade-off is Section 125 nondiscrimination testing, which checks whether highly compensated or key employees get disproportionate benefit. For most small businesses that testing is easier to pass than the comparability rule. A cafeteria plan requires a formal written plan document, which a benefits attorney or third-party administrator can draft.7eCFR. 26 CFR 54.4980G-5 – HSA Comparability Rules and Cafeteria Plans and Waiver of Excise Tax
Step 6: Enroll Employees and Run Payroll
Enrollment usually happens at open enrollment or when a new hire becomes eligible. The custodian supplies account-opening forms that employees complete with personal information and beneficiary designations, typically through an online portal. Each employee then elects a payroll deduction amount.
After every pay period, you send the withheld contributions to the custodian along with a file allocating each amount to the right employee account. Make sure whoever configures the payroll software codes HSA deductions as pre-tax. That one setting is where most first-year programs go wrong.
Tell employees plainly that the HSA belongs to them. If they leave, the account and every dollar in it go with them. That is a real difference from an FSA, where unused money can revert to the employer, and the portability tends to ease concerns about the higher deductible.
Step 7: Handle Year-End Reporting
Report total HSA contributions for each employee in Box 12 of Form W-2 using Code W. That figure includes both the employer contribution and the employee’s pre-tax payroll contributions. Employer contributions that are not excludable from income must also appear in Boxes 1, 3, and 5.8Internal Revenue Service. 2026 General Instructions for Forms W-2 and W-3 Contributions an employee makes directly to the custodian outside of payroll are not reported in Box 12.
The custodian takes care of Form 5498-SA (contributions) and Form 1099-SA (distributions) and sends copies to both the employee and the IRS. Employees file Form 8889 with their personal return to report contributions and distributions and to confirm withdrawals went to qualified medical expenses. Those two pieces are not your job, but employees will ask about them.
Penalties Worth Knowing
Three penalties account for most HSA problems.
Comparability violations. The 35% excise tax described above is the single biggest administrative risk for an employer.
Excess contributions. Any amount over the annual cap is subject to a 6% excise tax for each year it stays in the account. The fix is to withdraw the excess, plus any earnings on it, before the tax filing deadline for that year. This usually happens when employer and employee contributions are not tracked against the combined cap, or when an employee changes jobs mid-year and contributes through two employers.
Non-qualified distributions. If an employee withdraws HSA funds for anything other than a qualified medical expense, the amount is added to taxable income and hit with a 20% additional tax. The 20% penalty goes away once the employee turns 65, becomes disabled, or dies; after 65, non-medical withdrawals are still taxed as income but without the surcharge. Qualified medical expenses include prescriptions, dental, vision, and mental health care for the account holder, spouse, or dependents, as long as insurance does not reimburse the cost. Employees can pay out of pocket now and reimburse themselves from the HSA years later, provided the expense occurred after the account was established.9Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans
A Boundary on State Taxes
The triple tax advantage is a federal rule. California and New Jersey do not recognize HSA tax benefits: employee contributions are not deductible on the state return, and interest or investment gains inside the account are treated as taxable state income. Employees in those states still get the full federal benefit, but their state returns will look different. If you operate in either state, build that into how you explain the benefit so no one is caught off guard at tax time.