GSTR-1 JSON over 5 MB: how to split it for the GST portal

The GST portal won't accept a GSTR-1 JSON file larger than 5 MB, and zipping it doesn't help: the official guidance is to upload the data in several files.

The two limits

• Size: 5 MB per file. Confirmed by several secondary sources and by the offline tool's FAQ.
• Line items: older official FAQs say 19,000 line items per upload; newer guidance says 10,000. A line item is a row of tax detail, so an invoice with three rates counts as three. We default to the lower figure.

How to split without breaking the return

1. Split only between invoices. Never put half an invoice in one file and half in another.
2. Put each invoice in exactly one file. The portal merges files for the same period, but if a record it already has appears again, the new one overwrites the old.
3. Repeat the header (gstin, fp, gt, cur_gt) in every file.
4. Keep the period-level tables, such as the HSN summary and documents issued, together in one file, and upload it last. Splitting them risks a later file replacing an earlier one.

After uploading

Wait for each file to show “Processed” before uploading the next. Then generate the GSTR-1 summary on the portal and compare the document counts and taxable values with the totals you expected from your own books. The portal shows only the first 500 invoices per section, so use totals, not a visual scan.

If a file shows “Processed with Error”, the error code list explains each code, and the error fixer can propose corrections.