How to Fix HSN Summary Table 12 Mismatch in GSTR-1 & Tally

Filing your monthly or quarterly GSTR-1 returns requires ensuring that your detailed invoice data matches your consolidated HSN-wise summaries. The most common block during GSTR-1 JSON uploads is the HSN Summary Table 12 Mismatch.

This error indicates a discrepancy between the total tax values calculated from your sales invoices (reported in Tables 4, 5, 6, and 7) and the aggregate values grouped under HSN codes in Table 12. TallyPrime includes built-in diagnostics to isolate and correct these errors. This guide explains how to locate and resolve HSN summary mismatch issues in TallyPrime.

1. Common Causes of HSN Summary Table 12 Mismatches

Before initiating corrections, understand why these discrepancies occur in your TallyPrime database:

• Tax Rate Overrides: If a data entry operator manually alters the tax rate inside a sales voucher rather than relying on the rates configured in the Stock Item master, TallyPrime will log the override. This leads to invoice totals appearing under one tax rate, while the HSN summary reports the pre-configured item master rate.
• Missing HSN Configurations: When new inventory items are created quickly without assigning HSN codes, the corresponding sales are reported in Tables 4–7 but are omitted from Table 12, triggering a mismatch warning on the portal.
• Invalid Unit Quantity Codes (UQC): Declaring custom or non-standard measurement units (like BOXES or PACKS instead of the portal-recognized BOX or PAC) can cause the portal validator to reject Table 12 imports.

2. Step-by-Step: Resolving HSN Mismatches in TallyPrime

Follow these steps to locate and fix HSN exceptions before exporting your GSTR-1 return:

1. Go to Gateway of Tally > Display More Reports > GST Reports > GSTR-1.
2. Check the top panel of the GSTR-1 report. Locate the section named Uncertain Transactions (Correction Needed).
3. If this tab displays a non-zero count, double-click it to open the exceptions list.
4. Select the exception category: HSN/SAC details not provided or invalid or Mismatches in Tax Rates/Value of Supplies.
5. TallyPrime will list all affected vouchers. Press Enter on an entry to review the details.
6. Enter the corrected HSN code or tax rate in the mapping field and press Enter. The voucher is updated, and the transaction is cleared from the exceptions queue.

3. Resolving Quantity and UQC Mismatch Errors

If your GSTR-1 JSON file fails to upload due to UQC measurement code errors:

1. Go to the GSTR-1 report in TallyPrime and press Alt + V (Verify UQC).
2. TallyPrime lists all inventory items with custom measurement units that do not match the portal's standard Unit Quantity Codes.
3. Select the item, select the corresponding official UQC from the drop-down directory list (e.g. map Kgs to KGS-KILOGRAMS), and save.
4. TallyPrime will automatically update all historical sales vouchers for that stock item, correcting your Table 12 allocations.

4. Reconciling GSTR-1 Table 12 and Sales Ledger Totals

Before exporting your return file, perform a final audit check:

If these totals do not match, review the Summary of HSN/SAC section in your GSTR-1 report. The report details the taxable and tax values for each HSN code, making it easy to identify the specific item category causing the mismatch.

5. Reconciliations Checklist for GSTR-1 Table 12 Mismatch

6. Handling Non-GST Item Groupings

Transactions containing non-GST supplies (like transport charges or fuel) must be mapped to exempt SAC codes. Failing to assign HSN or SAC profiles to these charges causes Table 12 to omit the value, leading to sales register mismatches.

7. Re-exporting GSTR-1 JSON Payloads

After clearing uncertainties in TallyPrime, click Re-compute to rebuild GSTR-1. Re-export the clean JSON file and upload it to the GSTN portal to overwrite the invalid draft.

8. Resolving Negative Value Errors in Table 12

If credit notes exceed outward sales for a specific HSN in a month, Table 12 will report a negative value. The GST portal does not accept negative figures in Table 12. In these instances, you must carry forward the credit balance and adjust it in subsequent return periods.

9. Best Practices for Monthly Sales Reconciliation

Establish a process to compare GSTR-1 summaries with your sales registers before return uploads. Reconciling transaction details with HSN groupings ensures that errors are corrected in the ledger master prior to exporting draft JSON payloads.

10. Re-importing Updated Data Packages

If the GST portal reports that Table 12 contains invalid data after manual edits, delete the portal draft and re-upload the updated GSTR-1 JSON package from TallyPrime. This ensures that the online forms reflect the corrected database states. Using automated data import solutions like TrulyInvoice helps you bypass these manual corrections entirely by pre-validating HSN formats and matching unit quantity codes before they reach your local database, ensuring a clean and error-free GSTR-1 generation on every filing cycle. Establishing this pre-validation pipeline is the most secure way to eliminate GSTR-1 filing delays and avoid automated notices from the tax department. Ensure your team validates HSN codes during stock item creation to prevent future errors. Taking these validation precautions monthly saves valuable accounting time and protects the company against compliance failures. Regular database backups are also a key part of maintaining accounting safety. Set up a secure backup directory to preserve your work in case of sudden power cuts or network interruptions.