CSVIRIS CSV Tool

IRIS 250-record limit: split a large 1099 CSV

Each CSV you upload to the IRIS Taxpayer Portal can hold 250 records. The splitter below breaks a large file into numbered parts, repeats the IRS header in each, and checks every row on the way.

Your file never leaves this computer. Checking, fixing and splitting run in this browser tab. Nothing is uploaded, so SSNs and EINs stay with you. You can disconnect from the internet after the page loads and it still works for CSV and FIRE files.
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Combine two reports (QuickBooks contact list + 1099 totals)

QuickBooks Online has no single report with names, tax IDs, addresses and 1099 totals. Export the Vendor Contact List (with Tax ID and address columns) and the 1099 Contractor Summary, drop one above and the other here. Rows are joined by vendor name.

Match the exact header of your IRS template (recommended)

IRIS checks the header row word for word, and the IRS can change it each tax year. In the portal, open Upload CSV with Form Data, download the blank template for your form and tax year, and drop it here. The tool then writes your files under that exact header. It remembers the header row, never your data.

The limits that apply

250records per CSV file, header row not counted
100forms per submission from the Unsubmitted Forms page
100KBmaximum size of each uploaded file
1form type and 1 tax year per file

The 100KB size limit comes from the portal's own error message, shown in Publication 5717: "The file uploaded must be 100KB or less." A typical 1099-NEC row is about 150 to 200 bytes, so 250 rows fit easily. Rows with long business names, second address lines and state data are bigger, and those files hit 100KB first. The splitter checks both limits and starts a new file at whichever comes first.

Publication 5717 sets both numbers. After you upload a 250-row file and choose Add All, the forms wait on the Unsubmitted Forms page. You then submit them in groups of up to 100. To keep each file to one submission, choose 100 records per file in the tool.

How the split works

When the portal is not the right fit

The Taxpayer Portal suits anyone filing up to a few thousand forms. Past that, uploading dozens of files by hand is slow. Large filers usually use software that files through IRIS Application to Application (A2A), which takes XML transmissions up to 100 MB.

Frequently asked questions

Did the IRS raise the limit from 100 to 250?
Older IRS FAQs said 100 records per CSV. Publication 5717 (Rev. 9-2026), the guide for the 2027 filing season, says a CSV file can include up to 250 forms, header row not included.
Do I need the header row in every part?
Yes. IRIS reads the first row of every file as the header. A part without it is rejected.
Can I put 1099-NEC and 1099-MISC rows in the same file?
No. Each file holds one form type and one tax year.

Sources

Last reviewed November 1, 2026.

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