Employers have to offer health insurance when they average at least 50 full-time or full-time equivalent employees in the prior calendar year. That threshold, set by the Affordable Care Act’s employer shared responsibility rules, is the answer to when do employers have to offer health insurance under federal law. Businesses under 50 have no federal requirement to provide coverage. Businesses at or above it must offer a plan to full-time employees and their dependents, and for 2026 that plan has to cost the employee no more than 9.96% of household income for self-only coverage and pay at least 60% of covered medical costs.
How to Count to 50
The ACA calls a business at or above the threshold an Applicable Large Employer, or ALE. The count runs on the prior calendar year: if you averaged 50 full-time employees, including full-time equivalents, across last year, you’re an ALE this year.
Part-time workers count, even though you don’t have to individually offer them coverage. Add up their total monthly hours and divide by 120 to get your full-time equivalent number. A business with 35 full-time employees and enough part-timers to equal another 15 full-time equivalents is at 50.
There’s a narrow seasonal carve-out. If the only reason you cross 50 is seasonal workers who put in 120 days or fewer during the year, those workers can be excluded from the count.
Common ownership pulls separate companies together. Under IRS aggregation rules in Section 414 of the Internal Revenue Code, related businesses are treated as one employer for the headcount. Two companies you own with 30 full-time employees each add up to a single 60-employee ALE, and both are subject to the mandate.
Who Counts as Full-Time
A full-time employee under the ACA is anyone averaging at least 30 hours of service per week, or 130 hours per month. That definition drives the headcount, the list of workers you must offer coverage to, and the penalty math if something goes wrong.
You can measure hours one of two ways. The monthly measurement method looks at each employee month by month, which fits predictable schedules but forces real-time coverage decisions. The look-back measurement method uses a set period of 3 to 12 consecutive months to decide whether an employee averaged 30 hours a week; if they did, you treat them as full-time for a following stability period and keep their coverage in place through it, even if hours later drop.
Most employers with variable-hour workers use the look-back approach because it smooths out fluctuations. The trade-off is commitment: once someone locks in as full-time in the measurement window, you’re on the hook for coverage through the stability period.
What “Offering Coverage” Actually Means
A plan with your company’s name on it isn’t enough. The coverage has to clear two separate bars.
It has to be affordable. For 2026, that means the employee’s share of the monthly premium for the lowest-cost self-only option is less than 9.96% of household income. And it has to provide minimum value, meaning it’s designed to cover at least 60% of total allowed medical costs for a standard population, with substantial coverage of inpatient hospital and physician services.
Miss either bar, and if even one full-time employee gets subsidized Marketplace coverage, the penalty follows. The employee doesn’t have to ask you first. They apply, qualify for a premium tax credit, and the IRS comes back to you later.
You also have to offer coverage to dependents, defined here as biological or adopted children under 26. Spouses, stepchildren, and foster children are not dependents under the employer mandate, though plenty of employers cover spouses voluntarily.
Affordability Safe Harbors
Employers rarely know an employee’s household income, so the IRS lets you test affordability against data you actually have. Meeting any one of these safe harbors shields you from the affordability penalty even if the coverage would technically fail against real household income.
The Federal Poverty Line safe harbor keeps the employee’s monthly premium share at or under 9.96% of the federal poverty guideline for a single person, divided by 12. For 2026 plan years, employers use the 2025 guideline of $15,650, producing a maximum monthly employee contribution of about $130.
The Rate of Pay safe harbor uses the employee’s own wages. For hourly workers, multiply the hourly rate by 130 hours, then by 9.96%. For salaried workers, multiply monthly salary by 9.96%. Use the rate in effect on the first day of the plan year.
The W-2 safe harbor caps the premium share at 9.96% of the employee’s Box 1 W-2 wages divided by 12. It only works after the year closes, so it’s a retrospective check rather than something you can plan around.
The 90-Day Waiting Period Cap
You can make new hires wait before their coverage starts, but federal law limits the waiting period to 90 calendar days, weekends and holidays included. This applies to all group health plans regardless of employer size.
Orientation or probationary periods are allowed on top of that, but the 90-day clock starts the day the employee satisfies the plan’s eligibility conditions. A plan that makes employees eligible after a 60-day orientation must have coverage available by day 151 from the hire date at the latest. Earlier is always fine.
What It Costs to Get This Wrong
The IRS enforces two penalties under Section 4980H of the Internal Revenue Code, and which one applies turns on what the employer did.
If an ALE fails to offer minimum essential coverage to at least 95% of its full-time workforce and their dependents, and even one full-time employee receives a Marketplace premium tax credit, the penalty for 2026 is $3,340 per full-time employee annually. The first 30 employees are subtracted before the math. A company with 100 full-time employees would owe (100 − 30) × $3,340, or $233,800 for the year.
If the ALE does offer coverage but the plan is unaffordable or fails minimum value, the 2026 penalty is $5,010 per full-time employee who actually gets a subsidized Marketplace plan. There’s no 30-employee subtraction here, but only employees who went to the Marketplace and got a subsidy trigger the charge, and the total is capped at what the first penalty would have been.
Both are calculated monthly, at 1/12 of the annual figure, and assessed after the fact. You won’t get an immediate bill. The IRS sends Letter 226-J proposing the penalty first, and you have a window to respond before anything is finalized.
What You Still Have to File
Every ALE files annual information returns documenting the coverage it offered. That means Form 1094-C as a transmittal and one Form 1095-C per full-time employee, showing who was offered coverage, when, and the employee’s share of the lowest-cost premium.
For the 2026 calendar year, the deadlines are:
- Form 1095-C to employees by early 2027. The statutory deadline is January 31, though the IRS has consistently extended it to early March in recent years.
- Electronic filing to the IRS by March 31, 2027. Any employer filing 10 or more information returns of any type during the year has to file electronically.
- Paper filing by February 28, 2027, for the rare employer that still qualifies.
Filing penalties are separate from the coverage penalties above and can stack up quickly across a large workforce.
If You Have Fewer Than 50 Employees
No federal law requires you to offer health insurance. You can choose to, and if you do, a tax credit may be available. To qualify for the Small Business Health Care Tax Credit, you need:
- Fewer than 25 full-time equivalent employees
- Average annual employee wages of roughly $65,000 or less
- To pay at least 50% of each full-time employee’s premium
- To buy coverage through the Small Business Health Options Program (SHOP) Marketplace
The credit is largest for businesses with fewer than 10 employees averaging $27,000 or less in wages. Qualifying small businesses can claim up to 50% of their premium contributions (35% for tax-exempt organizations). SHOP enrollment is generally the only path to the credit.
One separate obligation kicks in earlier than the ACA mandate: federal COBRA rules apply to employers with 20 or more employees. COBRA doesn’t force you to offer a plan, but if you do, departing employees and their families have to be given the option to continue that coverage temporarily at their own expense. State laws can also add requirements or incentives for small-group coverage, so employers operating in multiple states should check locally rather than assuming the 50-employee federal line is the only one that matters.