What is Table 12 in GSTR-1?

Table 12 of GSTR-1 is the HSN-wise summary of outward supplies. Taxpayers must report the total quantity, taxable value, and rate-wise IGST, CGST, SGST, and Cess for each HSN/SAC code used during the tax period.

Why does an HSN summary mismatch occur in GSTR-1?

Mismatches occur when the sum of taxable values and tax amounts in your transaction invoices (reported in Tables 4, 5, 6, 7) does not match the consolidated totals reported in Table 12 (HSN Summary). Common causes include manual tax rate overrides in vouchers, missing HSN in item masters, or non-standard UQCs.

How do I fix Uncertain Transactions in GSTR-1 Table 12 in Tally Prime?

Go to Gateway of Tally > Display More Reports > GST Reports > GSTR-1. Click on 'Uncertain Transactions (Corrections needed)', locate 'HSN/SAC details not provided or invalid', enter the valid 6-digit or 8-digit HSN code, and press Enter to save.

What is a UQC mismatch error in Table 12 and how is it fixed?

This error occurs when the Unit Quantity Code (UQC) used in your transactions (e.g. PCS or BOX) does not match the default measurement unit accepted by the GST portal for that HSN code. In Tally Prime, press Alt+V (Verify UQC) inside the GSTR-1 screen and map the item to the statutory UQC.

How does TrulyInvoice prevent HSN summary mismatches during bill booking?

TrulyInvoice uses AI OCR to extract supplier line items with their exact 4, 6, or 8-digit HSN codes and statutory UQCs, auto-validates tax math, and pushes error-free F9 purchase vouchers directly into Tally via Port 9000, ensuring 100% downstream Table 12 alignment.

Fix GSTR-1 Table 12 HSN Summary Mismatch in Tally Prime [2026]

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.

Quick Answer: How to Fix GSTR-1 Table 12 HSN Mismatch in Tally Prime?

Go to Gateway of Tally > Display More Reports > GST Reports > GSTR-1. 1) Open 'Uncertain Transactions (Corrections needed)' and resolve 'HSN/SAC details not provided'. 2) Press Alt+V to map non-standard units to official GST UQCs. 3) Re-compute GSTR-1 and confirm Table 12 taxable value equals Table 4-7 invoice totals before exporting JSON.

Table 12 reports quantity, taxable value, and tax rates for all outward goods/services.
Turnover > ₹5 Cr requires 6-digit HSN codes; turnover <= ₹5 Cr requires 4-digit codes.
Use Alt+V in Tally Prime GSTR-1 to map custom units (e.g. 'Pcs') to official UQC ('PCS-PIECES').
TrulyInvoice AI automatically verifies HSN codes on supplier purchase bills to ensure zero downstream mismatches.

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:

Go to Gateway of Tally > Display More Reports > GST Reports > GSTR-1.
Check the top panel of the GSTR-1 report. Locate the section named Uncertain Transactions (Correction Needed).
If this tab displays a non-zero count, double-click it to open the exceptions list.
Select the exception category: HSN/SAC details not provided or invalid or Mismatches in Tax Rates/Value of Supplies.
TallyPrime will list all affected vouchers. Press Enter on an entry to review the details.
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:

Go to the GSTR-1 report in TallyPrime and press Alt + V (Verify UQC).
TallyPrime lists all inventory items with custom measurement units that do not match the portal's standard Unit Quantity Codes.
Select the item, select the corresponding official UQC from the drop-down directory list (e.g. map Kgs to KGS-KILOGRAMS), and save.
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:

Table 12 Total Taxable Value = Sum of (B2B Sales + B2C Sales + Exports + Advances) - Credit Notes

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.

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5. Reconciliations Checklist for GSTR-1 Table 12 Mismatch

Diagnostic Step	Audit Verification Target	Resolution Action in TallyPrime
Verify Stock Items	Confirm every inventory profile has a 6-digit HSN assigned	Run HSN/SAC Summary update helper
Check Manual Rates	Identify manually overridden tax rates in vouchers	Clear exceptions in the Uncertain Transactions tab
Reconcile Credit Notes	Confirm credit note adjustments are linked to the original invoice	Link invoice references in the allocations screen
UQC Mapping	Confirm custom units match portal standard UQCs	Re-map units via Alt + V in the GSTR-1 report

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.