How to avoid ACA sledgehammer and tack hammer penalties

Executive overview

Applicable large employers (ALEs) — those with 50 or more full-time employees — must offer affordable, minimum-value health coverage or face IRS penalties. Two distinct penalties apply: the sledgehammer for failing to offer coverage at all, and the tack hammer for offering coverage that is unaffordable or inadequate. Both are triggered only when at least one employee receives a premium tax credit on the ACA marketplace.

Avoiding both penalties comes down to six concrete compliance steps any HR team can manage.

The two penalty types

• Sledgehammer (4980H(a)): triggered when an ALE fails to offer minimum essential coverage to 95%+ of full-time employees and dependents; $2,970 per full-time employee per year in 2025 (first 30 employees excluded)
• Tack hammer (4980H(b)): triggered when coverage is offered but is unaffordable or lacks minimum value; $4,460 per employee receiving a marketplace tax credit in 2025
• Tack hammer applies only to employees receiving credits, not all full-time staff

Six steps to stay compliant

1. Determine ALE status — calculate average full-time employees plus FTEs from the prior calendar year; 50+ means the mandate applies
2. Offer minimum essential coverage to all full-time employees and their dependents
3. Ensure affordability — employee's share of lowest-cost self-only premium must not exceed 9.12% of household income (2025); use one of three IRS safe harbors: W-2 wages, rate of pay, or federal poverty line
4. Verify minimum value — plan must cover at least 60% of total allowed costs and include inpatient hospital and physician services; confirm with your benefits broker
5. Monitor eligibility and enrollment — track full-time status and hours worked; automate enrollment notices where possible
6. File forms 1094-C and 1095-C accurately — errors can trigger penalties even when coverage is compliant

If you receive a penalty notice

• Penalty notices arrive as IRS Letter 226-J; they are not final determinations
• Review the IRS's calculations against your filed forms
• Respond within 30 days with documentation if the IRS made an error