About and methodology

Who builds this

This site is built and maintained by Mike, an independent software developer who builds small, fast personal-finance calculators. Other tools in the same family include noovertimetax.com, statewage, ukmoneycalc and goldgramprice.

I am not a tax professional and this site is not tax advice. What I can offer instead is that every number here is recomputed in code from a primary source you can click through to, and that the code is tested against the worked examples the IRS published itself.

For a 2026 box 12 entry, the Code TT correction worksheet applies that source-first method workweek by workweek and exports the calculation for payroll review.

How we measured this

The eligibility check implements two documents and nothing else.

The first is IRS Fact Sheet FS-2026-13, issued 6 August 2026, which revises FS-2026-01 from January 2026. Topic F of that fact sheet, questions 19 through 25, is where the rules that decide your answer actually live. Those questions are all marked “added August 6, 2026”, so this is new material.

The second is Schedule 1-A (Form 1040), Part III, lines 14a through 21. The arithmetic in the tool follows those lines in order, including the two orderings that are easy to get wrong. The per return cap is applied at line 15, before the income reduction is subtracted at line 20, not after. And line 19 tells you to decrease the result to the next lower whole number, so 0.5 becomes 0 and 1.5 becomes 1. That is a floor, not a rounding, and getting it wrong shifts the answer by $100 a step.

The code is checked against every worked example the IRS gives. A correctly reported $10,000 in box 12 code TT carries through in full. An employer that reports $10,000 when it actually paid $5,000 leaves you able to consider only $5,000. An employer that reports $5,000 when it actually paid $10,000 leaves you able to consider only $5,000, unless it furnishes a Form W-2c, in which case the full $10,000 counts. If the IRS revises this guidance, those tests are what should fail first.

What this site will not tell you

Whether your state income tax also honors the deduction is a separate question with a separate answer in every state. It is not answered here. noovertimetax.com covers it.

Whether the caps and the income thresholds are indexed for inflation after 2025 is not addressed in FS-2026-13. I have not found a primary source that settles it, so the site says nothing either way rather than guessing.

Your actual return depends on your whole tax picture, not on one deduction. The tool gives an estimate of one line of one schedule.

Corrections

If a figure here is wrong, or the IRS has revised the guidance since the verified date shown at the top of each page, tell me and I will fix it and re-stamp the page.