What is ACA compliance? A 101 guide for employers

For US employers, the Affordable Care Act (ACA) influences everything, from how to track employee hours and when to offer health coverage to what to report. Missing even one requirement can lead to penalties or weeks of cleanup work. 

This article explains what ACA compliance is, who needs to follow it, the core requirements to plan around, and the risks of noncompliance. 

What is ACA compliance?

ACA compliance means following the ACA rules that apply to employers, especially the shared responsibility requirements and the reporting that confirms compliance. In practice, you’re answering one question: Do we have to offer health coverage, and can we prove we did it correctly?

Most of the pressure sits with applicable large employers (ALEs). A business qualifies as an ALE if it had 50+ full-time employees, including full-time equivalents (FTEs), in the prior calendar year. Part-time hours can push a business over the line even without 50+ full-time employees, because the ACA turns part-time hours into FTEs when deciding whether a business counts as a large employer.

If you qualify as an ALE, you must: 

• Offer minimum essential coverage (MEC) to enough eligible full-time employees and their dependants.
• Ensure the offer meets minimum value.
• Keep employee costs within the IRS affordability standard.

The IRS updates the ACA affordability percentage annually rather than keeping it fixed. For plan years beginning in 2026, the IRS has set the affordability threshold at 9.96%.

Finally, you must document coverage on Forms 1094-C and 1095-C, referred to as ACA reporting or ACA filing. These forms outline what coverage you offered, to whom, and when, allowing the IRS to verify whether you met the employer mandate. 

Who needs to be ACA compliant?

ACA compliance depends on whether the law counts you as a large employer. Here’s who typically falls under the rules:

• ALEs: You’re considered an ALE if your workforce averaged 50 or more full-time employees, including FTEs, in the prior calendar year. Under the ACA, a full-time employee is someone who averages 30 hours per week (or 130 hours in a month).
• Employers with lots of part-time hours: The ACA doesn’t let you stay small on paper by splitting work across part-time roles. To calculate FTEs for the ALE test, total all part-time hours for the month and divide by 120 to convert those hours into FTEs.
• Religious organizations: Churches and similar religious employers also fall under ALE rules. Some may qualify for exemptions tied to specific coverage types, such as certain contraceptive coverage requirements, rather than a blanket exemption from ACA responsibilities.

If you fall under the ALE threshold, you aren’t required to offer health coverage under the mandate. However, some smaller employers provide ACA-aligned coverage anyway, because it strengthens their employee benefits package and fits their hiring and retention goals.

ACA compliance requirements

ACA requirements shift based on employer size and on how you structure coverage. 

Large employers (50+ full-time employees or FTEs)

As an ALE, you’re legally required to provide benefits meeting federal standards, including an employer-sponsored health insurance structure that covers enough eligible employees. The employer mandate generally looks at whether you offered MEC to at least 95% of eligible full-time employees and their dependents. 

The offer must also meet the IRS affordability standard, meaning the employee’s share of self-coverage cannot exceed a set percentage of income. Since employers usually don’t have access to an employee’s full household income, the ACA allows safe harbors that use data you control—like W-2 wages or rate of pay—to assess affordability. 

Plus, large employers must offer coverage that meets the minimum value standard, which generally means the plan pays at least 60% of the total allowed cost of benefits for a standard population and includes substantial coverage of physician and inpatient hospital services. 

A “standard population” just means an average mix of people using care, not the company’s exact claims history. These minimum value and affordability rules shape what health insurance benefits you offer and how you price employee contributions.

Lastly, employers must document offers of coverage, enrollment details, and related data on Forms 1094-C and 1095-C. Some states, like California and New Jersey, may add their own individual mandate or coverage reporting requirements for certain employers and carriers. 

Small employers (less than 50 full-time employees or FTEs)

If your headcount stays under 50 FTEs, the ACA’s employer shared responsibility mandate generally doesn’t apply.

However, a lot of smaller employers still choose to offer ACA-aligned plans as part of their small business employee benefits package because the benefits influence offer acceptance, primarily when competing with larger companies that already provide coverage. In that case, the question shifts from “What are we required to do?” to “What do candidates expect from us?”

For a fully insured small-group plan, the carrier usually handles the 1095-B side of coverage reporting. But if you self-insure, you’ll need to complete annual coverage reporting in-house using Forms 1094-B and 1095-B, even though the employer mandate doesn’t apply.

Any size employer

Regardless of size, maintaining HR compliance means delivering required employee notices tied to coverage access and plan transparency. Common examples include: 

• The Marketplace notice, which tells new hires about their options on the public health insurance marketplace.
• The Summary of Benefits and Coverage (SBC), which is a standardized plain-language snapshot of what your health plan covers and what it costs.
• Notices about plan changes whenever you change plan terms in ways employees need to know about.

You also need consistent eligibility tracking. Variable-hour and seasonal workers can change who qualifies from month to month, so the calculation method and documentation must remain accurate year-round.

Finally, some requirements depend on filing volume or plan type. Employers that file 250 or more W-2s generally must report the value of employer-sponsored coverage on those W-2s. In Plus, sponsors of self-insured plans may owe PCORI fees—an annual charge that funds the Patient-Centered Outcomes Research Institute—reported on Form 720.

ACA noncompliance penalties

Here are some common ACA penalties employers run into: 

• 4980H(a): This penalty applies if an employer fails to offer the MEC to at least 95% of full-time employees and at least one full-time employee receives a premium tax credit (PTC). For calendar year 2026, the indexed annual amount is $3,340 per full-time employee, excluding the first 30 full-time employees from the calculation. 
• 4980H(b): This penalty applies when an employee gets the PTC because the employer’s offer didn’t meet the affordability standard or the minimum value standard, or both. For calendar year 2026, the indexed annual amount is $5,010 per impacted full-time employee, and it’s capped so it can’t exceed what you owe under 4980H(a). 
• Late or incorrect ACA reporting (Forms 1094-C and 1095-C): The IRS can issue per-return penalties when information returns or employee statements are late, inaccurate, or missing. For returns due in 2026, penalties start at $60 per return (up to 30 days late) and can rise up to $340 per return after 1st August for intentional disregard.
• Missing required notices or plan documentation: Separate penalties can apply when required benefit disclosures don’t go out correctly. For example, agencies periodically publish civil monetary penalties and fines for SBC failures, and the Employee Retirement Income Security Act (ERISA)-related penalties can apply when participants request plan documents and the employer doesn’t provide them on time. Courts can impose penalties of up to $110 per day until the employer complies.

Staying ACA compliant with Oyster

ACA compliance is a US federal requirement, but it also applies to international companies employing people in the US. If you miss the mark, you face huge penalties, and the cleanup work usually falls to People Ops, payroll, and whoever owns benefits administration.

As you expand into the US, the hardest part isn’t learning one rule. It’s keeping healthcare mandates aligned with employee classification and tax reporting when you don’t have local expertise in-house. That’s where ACA solutions, such as professional employer organization (PEO) partnerships, become valuable.

Oyster’s US PEO solution supports payroll, benefits, and compliance workflows in the US, so you don’t have to piece it together every time regulations or reporting expectations change.

About Oyster

Oyster is a global employment platform designed to enable visionary HR leaders to find, engage, pay, manage, develop, and take care of a thriving distributed workforce. Oyster lets growing companies give valued international team members the experience they deserve, without the usual headaches and expense.

Oyster enables hiring anywhere in the world—with reliable, compliant payroll, and great local benefits and perks.