2026 benefits math: new ACA affordability percentage, HSA and HDHP limits

What changed The IRS published its annual indexing adjustments for health and welfare plans. The two that matter most to employers: - The ACA required contribution percentage used for the affordability safe harbors has been reset for plan years beginning in 2026. If your lowest-cost self-only plan crosses the line, you are exposed to employer mandate penalties. - HSA contribution maximums, HDHP minimum deductibles and out-of-pocket maximums, health FSA salary reduction limits and dependent care limits all moved. What HR needs to do - Re-run the affordability safe harbor calculation (W-2, rate of pay, or federal poverty line) against your actual 2026 employee-only contribution. Do this per pay group, not company-wide. - Confirm your HDHP still meets the minimum deductible so employees remain HSA-eligible — a plan design that drifted below the floor silently disqualifies contributions. - Update payroll deduction caps for HSA, health FSA and dependent care. - Correct any benefits guide, offer letter template or portal screen that still quotes prior-year numbers. Why it matters Affordability failures do not show up until the IRS issues a Letter 226-J two years later, by which point the population is fixed and the penalty is arithmetic.