Complete Guide to HSA Excess Contributions & IRS Penalties
Health Savings Accounts (HSAs) provide a triple-tax advantage: contributions are tax-deductible (or pre-tax via Section 125 payroll), growth is tax-free, and withdrawals for qualified medical expenses are exempt from federal and state taxes. However, because of these substantial tax preferences, the Internal Revenue Service enforces strict contribution ceilings under Internal Revenue Code (IRC) Section 223.
Statutory Annual Limits (2024 - 2026)
| Tax Year | Self-Only HDHP | Family HDHP | Catch-Up (Age 55+) |
|---|---|---|---|
| 2026 (Projected) | $4,400 | $8,750 | $1,000 |
| 2025 | $4,300 | $8,550 | $1,000 |
| 2024 | $4,150 | $8,300 | $1,000 |
How HSA Excess Contributions Occur
Taxpayers frequently trigger excess contributions due to four common circumstances:
- Partial-Year HDHP Enrollment: If you start or end high-deductible health plan (HDHP) coverage mid-year, your contribution limit is prorated on a monthly basis (number of months covered on the 1st of the month divided by 12).
- Employer and Employee Contributions Combined: Both employer wellness contributions (reported in Box 12 of Form W-2 with Code W) and employee payroll salary reductions count toward the same annual dollar ceiling.
- Disqualifying Healthcare Coverage: Having a general-purpose Flexible Spending Account (FSA), Health Reimbursement Arrangement (HRA), or enrolling in Medicare Part A or Part B disqualifies you from making HSA contributions.
- Failed Last-Month Rule Testing Period: If you contributed the full annual limit under the Last-Month Rule in a prior December but failed to maintain HDHP coverage for the full subsequent 12-month testing period.
The 6% Excise Penalty Under IRC § 4973
Excess contributions that remain in an HSA at the close of the tax year are subject to a 6% excise tax penalty under IRC § 4973. The penalty is calculated on the lesser of:
- The total excess contribution amount, OR
- The fair market value (FMV) of the HSA account as of December 31.
The excise tax is reported on IRS Form 5329, Part VII. Crucially, the penalty is not a one-time fee; it recurs every single year until the excess is formally eliminated.
The Net Income Attributable (NIA) Formula
To avoid the 6% excise penalty entirely, the taxpayer must withdraw the excess contribution along with any earnings earned on that excess before their tax return due date (plus extensions). The earnings are governed by Treasury Regulation § 1.408-11:
If the account incurred an investment loss during the period, the NIA is negative, which reduces the total dollar amount that must be distributed from the HSA.