TIN format in the IRIS CSV
Each TIN needs its dashes and a TIN type that agrees with them.
| TIN type | Format | Who can use it (tax year 2025 guidelines) |
|---|---|---|
| SSN | XXX-XX-XXXX | Payer or recipient |
| EIN | XX-XXXXXXX | Payer or recipient |
| ITIN | XXX-XX-XXXX | Recipient |
| ATIN | XXX-XX-XXXX | Recipient |
| QI-EIN | XX-XXXXXXX | Recipient |
| UND (undeterminable) | XXXXXXXXX | Recipient |
The payer TIN type must be SSN or EIN. The recipient TIN type is required whenever a recipient TIN is entered.
The usual problems
- No dashes. 123456789 could be either kind. You have to know which from the W-9.
- Dropped leading zero. A TIN stored as a number loses a leading 0 and shows 8 digits.
- Scientific notation. 1.23457E+08 cannot be recovered from a CSV.
- Wrong pairing. An EIN-shaped number with TIN type SSN.
Perfrow keeps TINs as text, restores a dropped zero and tells you, reads the type from the dashes when they are there, and otherwise decides from the name or from your setting. Every assumption is listed for you to check. TINs never leave your browser, and the report masks them.
Rules here follow the tax year 2025 guidelines, the newest the IRS has published as of 10 November 2026. Tax year 2026 guidelines were not posted yet. The IRS says the copy inside the Taxpayer Portal is the current one, so check it there before you file.
Fix the whole file at once
Drop in your blank IRIS template and your spreadsheet. Perfrow cleans every row, tells you which ones need you, and writes CSVs of at most 250 records. It runs in your browser, so names and TINs stay on your computer.
Open the 1099-NEC CSV fixerQuestions
- Does the IRIS CSV need dashes in the SSN or EIN?
- Yes. The guidelines give EIN as XX-XXXXXXX and SSN as XXX-XX-XXXX. Only the UND type is written as nine digits with no dash.
Other answers: All 54 columns · Required fields · Character limits · State codes · 250-record limit · Why files get rejected · Scientific notation · ZIP code format · Date format · Line breaks · Extra spaces · Periods and # · $0.00 cells · Y/N check boxes · Tax year · Error types · Headers do not match · From QuickBooks · Key dates