Fix "Data Invalid" on HSN files in the GST offline tool

The GST Returns Offline Tool shows "Data Invalid" on an HSN summary file when the file isn't named exactly hsn(b2b).csv or hsn(b2c).csv. Rename the file, keep the column headers from the tool's own template, and import it again under the matching HSN section.

We found this on 6 November 2026, importing a month of GSTR-1 files into version 3.2.4 of the tool, the current version as of November 2026. The message never says the file name is the problem, so it sends you looking for a mistake in the numbers instead.

Why the HSN summary now comes as two files

Table 12 of GSTR-1 is the HSN-wise summary of what you sold. GSTN has split it into two tabs, "B2B Supplies" and "B2C Supplies", and you enter each one separately (GSTN advisory). B2B means sales to GST-registered buyers, and B2C means sales to everyone else.

The offline tool followed. Its release notes for version 3.2.2 say HSN is split into HSN(B2B) and HSN(B2C) supplies. Its template folder now holds hsn(b2b).csv and hsn(b2c).csv, next to an older single hsn.csv (Returns Offline Tool download).

The portal also checks the split against the rest of your return (GSTR-1 FAQs).

• B2B tab: if you report B2B sales in other tables, this tab can't be left empty. The portal stops you generating the summary.
• B2C tab: leaving it empty brings a warning, but you can go on.
• Totals: each tab is compared with the matching tables. A difference of more than 10%, up or down, brings a warning.
• HSN digits: at least 4 digits if your turnover last year was up to ₹5 crore, at least 6 above that.

The fix for "Data Invalid" on HSN files

In our test, every other section imported on the first try. Only the HSN files failed, and they failed whatever was inside them. Once renamed, they went straight in.

1. Find the two HSN files your billing software exported. They may be called something like hsn_b2b.csv or HSN summary B2B.csv.
2. Rename the B2B file to exactly hsn(b2b).csv, with round brackets and no spaces.
3. Rename the B2C file to exactly hsn(b2c).csv.
4. Compare the first row of each file with the template of the same name in the tool's Section_wise_CSV_files/GSTR1 folder.
5. Import each file under its own HSN section, as described below.

The download still includes an older hsn.csv template. Since you now report B2B and B2C separately, use the two new names instead.

What the column headers must say

The tool matches columns by their header names, so the first row has to read exactly like the template. In the official hsn(b2b).csv and hsn(b2c).csv templates the headers are these, in this order.

1. HSN
2. Description
3. UQC
4. Total Quantity
5. Total Value
6. Taxable Value
7. Integrated Tax Amount
8. Central Tax Amount
9. State/UT Tax Amount
10. Cess Amount
11. Rate

UQC is the unit code, written the way the template shows it, like NOS-NUMBERS. In the files we imported, service lines (SAC codes starting with 99) left UQC and quantity blank and went in without trouble.

Keep amounts to two decimal places. The tool's user manual lists more than two digits after the decimal as a reason it rejects data.

How to import, step by step

These steps follow the user manual that comes in the tool's download.

1. Open the tool, click NEW, choose GSTR-1/IFF, your GSTIN, the year and the month, then PROCEED.
2. Click IMPORT FILES.
3. From Select Section, pick the section, such as "HSN-wise summary of outward supplies (B2B) - 12".
4. Under One section at a time, click IMPORT CSV and choose the matching file.
5. Confirm with Yes, wait for the success message, then click BACK and check the rows.
6. Repeat for every section, including Table 13 (documents issued), which the portal treats as compulsory once you report sales.
7. Click VIEW SUMMARY and compare the totals with your sales register.

One thing catches people out. For summary sections such as HSN, a later upload overwrites the whole section uploaded before. So import the full month's file each time, never a part.

Our test covered register, b2b, b2cl, b2cs, cdnr, cdnur, hsn_b2b, hsn_b2c and docs, the files our system exports. Every GSTR-1 section imported (the register is for your CA, not for import), and the totals matched.

Other reasons the tool says "Data Invalid"

The tool's release notes describe an error, "Column Headers Missing/Mismatch or Data Invalid", for problems with column headers. If the file name is right and it still fails, the user manual lists these as common causes of rejected imports.

• Headers changed: a column header renamed, retyped or missing.
• Dates: written as dd-mmm-yyyy, like 01-Jul-2017. Future dates, or invoice dates after the tax period, are refused.
• Invoice numbers: at most 16 characters, letters and numbers, with only a forward slash or hyphen. No duplicates.
• GSTIN: 15 characters with no spaces. Your own GSTIN in the receiver column also causes an error.
• Decimals: two digits after the decimal point, no more.
• HSN: numbers only.
• Wrong section: importing a file under a section it doesn't belong to.

Quick answers

Which file name does the offline tool want for the HSN summary?

hsn(b2b).csv for sales to registered buyers and hsn(b2c).csv for sales to everyone else. Those are the names of the templates in version 3.2.4, as of November 2026.

Can I leave the B2C HSN tab empty?

The portal shows a warning but lets you go on. The B2B tab is different: if other tables have B2B sales, you can't generate the summary without it.

Does the right file name mean my return is correct?

No. It only gets the data into the tool. Your CA should still check the summary before you generate the file and upload it on the portal.

If you'd like help

Pixelvile's GST invoicing gives your CA each month's GSTR-1 files already named the way the offline tool expects, and our guide to GST invoices paid by UPI covers the invoices themselves. Ask for a free audit of how you bill today, or WhatsApp us on +91 62918 31815.