IRIS CSV ZIP code format
Digits only: exactly 5, 9 or 12 of them. No dash. Leading zeros kept.
| In your sheet | Problem | Write it as |
|---|---|---|
| 27101-3345 | Dash | 271013345 |
| 2134 | Excel dropped the leading zero | 02134 |
| 7.52E+08 | Scientific notation, digits lost | Retype all 9 digits |
| K1A 0B1 | Foreign postal code | Up to 9 letters and numbers, with the country code set |
The formatting guidelines give the rule for a domestic address as "Length: Exactly 5, 9 or 12 characters" and "Digits only". Publication 5717 adds: set the column to Text, and do not enter a dash.
ZIP codes in Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, Rhode Island, Vermont and Puerto Rico start with 0, so a column stored as numbers loses a digit on every one of them.
Perfrow removes the dash, puts a dropped zero back (and tells you it did), and flags any other length.
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 IRIS accept ZIP+4 with a dash?
- No. The guidelines say digits only, and Publication 5717 says not to enter a dash. Write 271013345.
- Why did my ZIP code lose its first zero?
- The spreadsheet stored it as a number. Format the column as Text, or let a tool restore the zero.
Other answers: All 54 columns · Required fields · Character limits · State codes · 250-record limit · Why files get rejected · Scientific notation · 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 · TIN format · Key dates