One tax year per file
Every row in a file must carry the same tax year, and the template must be the one for that year.
Publication 5717, section 3.5: "You will only be able to upload one tax year and one form type at a time." Its reject table adds: "Ensure each template contains the same tax year. If another tax year needs to be reported, a separate template will need to be created for each tax year."
| Situation | What to do |
|---|---|
| 2026 forms plus two late 2025 forms | Two files: one on the 2026 template, one on the 2025 template |
| 1099-NEC and 1099-MISC for the same vendors | Two files, one per form type |
| Last year's filled-in file reused | Download a fresh template. Publication 5717 recommends a new template each time |
In the portal you pick the tax year and form type before you download the template. IRIS takes tax year 2022 and later.
Perfrow writes the tax year you choose into column B of every row, so a mixed column cannot happen. Run it once per year.
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
- Can one IRIS CSV file contain two tax years?
- No. Publication 5717 says one tax year and one form type at a time.
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 · Error types · Headers do not match · From QuickBooks · TIN format · Key dates