The Affordable Care Act (ACA) has been the law of the land for over a decade, but ACA compliance remains a source of confusion — and costly mistakes — for many mid-size employers. The rules are complex, the penalties are real, and the requirements change regularly.

Here's what every employer with 50 or more full-time equivalent employees needs to know.

The Employer Shared Responsibility Provision

The ACA's employer mandate — formally known as the Employer Shared Responsibility Provision — requires Applicable Large Employers (ALEs) to offer minimum essential coverage to their full-time employees and their dependents, or face potential penalties.

You are an ALE if you employed an average of 50 or more full-time equivalent employees in the prior calendar year.

Part-time employees count toward this threshold on a pro-rated basis. A business with 30 full-time employees and 40 part-time employees working 20 hours per week would have 30 + (40 × 20/30) = approximately 57 full-time equivalents — making it an ALE subject to the employer mandate.

What Coverage Must You Offer?

To avoid penalties, ALEs must offer coverage that meets two standards:

Minimum Value

The plan must cover at least 60% of the total allowed cost of benefits. Most major medical plans offered by reputable carriers meet this standard, but it's worth confirming.

Affordability

The employee's required contribution for self-only coverage cannot exceed a specified percentage of their household income. For 2026, the affordability threshold is 9.02% of household income.

Since employers typically don't know employees' household incomes, the IRS provides three safe harbors for determining affordability:

1. W-2 Safe Harbor — contribution doesn't exceed 9.02% of the employee's W-2 wages
2. Rate of Pay Safe Harbor — contribution doesn't exceed 9.02% of the employee's monthly rate of pay × 130 hours
3. Federal Poverty Line Safe Harbor — contribution doesn't exceed 9.02% of the federal poverty line for a single individual

ACA Reporting Requirements

ALEs must file annual reports with the IRS and provide statements to employees:

• Form 1095-C — provided to each full-time employee, documenting the coverage offered and the employee's share of the premium
• Form 1094-C — the transmittal form filed with the IRS, summarizing the employer's coverage offerings

Key deadlines:

• Employee statements (1095-C): Must be furnished by March 3 of the following year
• IRS filing (1094-C + 1095-C): March 31 for electronic filers (required for employers filing 10 or more returns)

Missing these deadlines or filing incorrect information can result in penalties of up to $330 per return, with higher penalties for intentional disregard.

Common ACA Compliance Mistakes

Misclassifying Employees

The ACA uses a specific definition of "full-time employee" — someone who works an average of 30 or more hours per week. Employers who classify workers as part-time to avoid the mandate — without actually limiting their hours — face significant penalty exposure.

Failing to Track Variable-Hour Employees

Employees whose hours vary from week to week must be tracked during a "measurement period" to determine whether they qualify as full-time. Failing to implement a proper measurement and stability period system is one of the most common compliance errors.

Affordability Errors

Offering coverage that technically meets minimum value but isn't affordable — because the employee's required contribution is too high — can trigger penalties if an employee receives a premium tax credit through the Marketplace.

Late or Incorrect Reporting

1094-C and 1095-C filings must be accurate and timely. Errors in employee information, coverage codes, or affordability calculations can trigger IRS notices and penalties.

Staying Ahead of Changes

ACA regulations and affordability thresholds change annually. Employers who set their contribution strategy once and never revisit it risk falling out of compliance as the rules evolve.

Working with a benefits advisor who monitors regulatory changes and proactively updates your compliance strategy is the most reliable way to stay ahead of ACA requirements — and avoid the penalties that come with falling behind.