Prices the last-month rule before the IRS prices it for you
| Eligible months counted in 2026 | — | months |
|---|---|---|
| Month-by-month limit | — | $ |
| Limit that governs this election | — | $ |
| Employee + employer total | — | $ |
| Excess contribution for 2026 | — | $ |
| 6% excise per year on the excess | — | $ |
| Added back to income if the testing period fails | — | $ |
| Income tax + 10% additional tax on that add-back | — | $ |
| Total 2026 exposure | — | $ |
This page is the working piece. The full pack has everything below.
Prices the last-month rule before the IRS prices it for you
IRS Rev. Proc. 2025-19 sets the 2026 HSA limits ($4,400 self-only, $8,750 family, $1,000 age-55 catch-up). A CPA bills $150-$400 an hour in 2026 and a Form 1040-X amended return runs $200-$1,500 to unwind one wrong HSA year.
Buy the full version — $60It takes one 2026 HSA election - coverage tier, the date HDHP coverage started, the last month of eligibility, catch-up age, employee and employer dollars - and returns the month-by-month limit, the last-month-rule limit, which one governs, any excess and its 6% excise, and what the 13-month testing period costs if eligibility lapses.
US payroll and benefits administrators who process mid-year HSA elections, plus the CPAs and enrolled agents who clean them up in January. If you have ever had to decide whether an employee who joined the HDHP in August may fund the full $8,750, this is that decision, priced.
A general chatbot answers from whatever year's table it learned, and nothing in the answer tells you which year you got: 2025 was $4,300 and $8,550, 2026 is $4,400 and $8,750. Generic HSA calculators stop at the annual limit, so they never price the 13-month testing period, which is where the real money sits.
Every calculation is free, unlimited and key-free: proration, the last-month rule, the excise and the testing-period add-back, in the popup and on the web page. The $60 key changes the axis, not the answer - it exports the audit as a .csv you own and sets the two reminder alarms.
A CPA bills $150 to $400 an hour in 2026, and unwinding one wrong HSA year through a Form 1040-X amended return runs $200 to $1,500. One August-start family election carries $5,104.17 of testing-period add-back; at a 24% marginal rate that is $1,735.42 of tax.
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