What it checks
- Structure. Every record is a known Publication 1220 type, payee (B) records sit under a payer (A) record, and each payer has its end-of-payer (C) record.
- Totals. The number of payees and each amount total in the C record against the B records actually in the file, the mismatch FIRE used to reject files for.
- Amounts. Every payment amount is read with its sign, including the old overpunch format for negatives, and shown against the box it belongs in.
- Payees. Which TINs are SSNs, ITINs, ATINs or EINs, whether a person's name splits cleanly using the name control, and addresses too long for one line.
- Corrections. Corrected (G or C) records are counted and listed separately.
It reads 1099-NEC, MISC, INT, DIV, R, G, K and S, 1098, 1098-T and W-2G files for tax years 2022 and later, and previews every form.
Why check it now
The IRS retires FIRE on November 19, 2026, so you can no longer upload this file there to find out what's wrong with it. From the 2027 filing season, 1099s go through IRIS. If your file checks out, the same page turns it into the IRIS Taxpayer Portal CSV files for $49 per payer. Checking stays free.
It runs entirely in your browser. Your file, with its SSNs and TINs, is never uploaded to me or anyone else.