Prices the last-month rule before the IRS prices it for you
Eligible months counted in 2026
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months
Month-by-month limit
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$
Limit that governs this election
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$
Employee + employer total
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$
Excess contribution for 2026
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$
6% excise per year on the excess
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$
Added back to income if the testing period fails
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$
Income tax + 10% additional tax on that add-back
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$
Total 2026 exposure
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$
The 2026 numbers, straight from the source Carries the IRS Rev. Proc. 2025-19 figures for 2026: $4,400 self-only, $8,750 family, $1,000 age-55 catch-up, HDHP minimum deductible $1,700 / $3,400 and out-of-pocket cap $8,500 / $17,000. Source: IRS Rev. Proc. 2025-19, released May 1, 2025. The 2025 figures it replaces were $4,300 and $8,550.
Month proration against the last-month rule HDHP family coverage starting August 1, 2026 buys 5 eligible months, so the month-by-month limit is $3,645.83 while the last-month rule allows the full $8,750 - the tool shows both and says which one governs.
The 13-month testing period, priced Take the last-month rule and lose eligibility before December 31, 2027 and the $5,104.17 difference goes back into gross income with a 10% additional tax on top: $1,735.42 at a 24% marginal rate.
6% excise on what is already over Contributions above the governing maximum draw a 6% excise tax for every year they sit in the account: a $4,375 excess on a half-year family election costs $262.50 a year until it is withdrawn.
Keep the audit and the two dates The $60 key writes the finished audit to a .csv you own and arms browser alarms for the December 1, 2026 eligibility snapshot and the December 31, 2027 testing-period close.