HSN-Wise Summary in GSTR-1 (Table 12): What to File, Which Digit Length, and How Billing Software Generates It

Every HSN code you set against an item in your billing software has one monthly destination: Table 12 of GSTR-1. The HSN wise summary in GSTR-1 is built entirely from the codes, units and quantities sitting in your item master, which is why a shop can invoice happily all month and still get stuck on filing day. A missing code, a stray second code for the same product, or a unit that does not match the portal's list all surface here, not on the invoice.

This post covers what Table 12 asks for, which digit length applies to you, the common reasons the summary does not tie back to your sales, and what a billing system has to do so you are not reconciling it by hand every month.

What Table 12 actually reports

Most of GSTR-1 reports your month document by document: B2B invoices in Table 4, large B2C interstate invoices in Table 5, consolidated B2C supplies in Table 7, credit and debit notes in Table 9, and so on. Table 12 reports the same month from a completely different angle. It groups your outward supplies by HSN code instead of by invoice or customer.

A few consequences follow from that:

It is an aggregate table. One row covers every invoice in the period that shares the same HSN code, tax rate and unit of measure.
You cannot fix a single bill here. Table 12 is where a messy item master shows up as a total that does not match the rest of the return.
It is mandatory, not optional. Nil-rated and exempt outward supplies belong in it too, even though they carry no tax.
Services are included. Service lines are reported with their SAC code in the same table.

How many HSN digits to report

The digit length is driven by your aggregate annual turnover in the previous financial year, not by the product.

Aggregate annual turnover (previous FY)	Minimum digits in Table 12	Applies to
Up to Rs. 5 crore	4 digits	Mandatory for B2B supplies; strongly recommended for B2C
Above Rs. 5 crore	6 digits	All outward supplies, B2B and B2C
Any turnover	8 digits	Exports, imports, and the notified chemical products that always require 8 digits

Two practical notes. First, reporting more digits than required is always acceptable, because a 6 or 8 digit code contains the 4 digit heading inside it. If you are near the Rs. 5 crore line, storing 6 digits in the item master now saves you a re-tagging exercise next April. Second, the digit rule for Table 12 is the same rule that governs your invoices, so if you have already followed our guide on how many digits of HSN code you need on a GST invoice, your summary is already at the right depth.

What each Table 12 row contains

For every HSN row you report:

HSN or SAC code, now picked from the portal's own HSN master rather than typed freely.
Description, auto-populated from that master once the code is selected.
UQC (unit quantity code), the standardised unit such as PCS, KGS, MTR or NOS.
Total quantity supplied under that code for the period.
Rate of tax applicable to the row.
Total taxable value.
Tax amounts: IGST, or CGST and SGST, plus cess where it applies.

The portal has also split Table 12 into separate B2B and B2C tabs, and it now cross-checks the taxable value you report here against the values declared in the invoice tables, flagging differences before you file. That validation is the reason a summary that used to pass quietly can suddenly raise a warning on the same data.

Where the HSN summary usually breaks

In a retail shop, almost every Table 12 problem traces back to the item master:

Items with no HSN code at all, usually ones added in a hurry at the counter.
The same product tagged with two different codes by two different staff members, splitting one row into two.
Wrong or inconsistent UQC, for example a product billed sometimes in PCS and sometimes in BOX, which makes the total quantity meaningless.
Service lines skipped, such as repair or installation charges added as a free-text line with no SAC.
Nil-rated and exempt goods left out on the assumption that no tax means no reporting.
Codes at mixed depth, a few 8 digit codes among mostly 2 digit chapters, which fails the minimum-digit check.

If you are unsure about a code before you save it, our HSN code finder lets you search by product name and confirm the code and rate, and how to read the HSN code master explains why a chapter, heading and sub-heading are different lengths of the same number.

How billing software generates Table 12

Good billing software does not build the HSN summary at filing time. It builds it continuously, as a by-product of billing:

The item master is the single source of the code, so the HSN, UQC and tax rate are attached the moment a product is created, not chosen per bill.
Each invoice line stores the code, unit, quantity, rate and taxable value as they stood when the bill was raised, so an item edited later does not silently rewrite last month's return.
At month end the system groups those lines by HSN plus rate plus UQC and sums quantity, taxable value and each tax head, which is exactly the shape Table 12 wants.
The export is trimmed to your required digit length, and items missing a code are listed as exceptions instead of being dropped.

That last point matters more than the export format. An exception list of twelve untagged products is a ten minute fix. A total that is quietly short by those twelve products is a notice waiting to happen.

A ten minute monthly check

Run the HSN summary report in your billing software for the month.
Check the exception list for items with no HSN or no UQC, and fix them in the item master.
Confirm every code has at least your required number of digits.
Match the total taxable value in the summary against your total outward supplies for the month.
Only then upload or key the figures into Table 12, and read any portal warning before filing rather than after.

Frequently Asked Questions

Is Table 12 mandatory for small shops?

Yes. The HSN-wise summary is a required part of GSTR-1 for every regular taxpayer. What changes with size is the depth: up to Rs. 5 crore turnover you report 4 digit codes and the requirement is mandatory for B2B supplies, while above Rs. 5 crore you report 6 digits for all supplies. Composition dealers file GSTR-4 instead and are outside this table.

Do I report nil-rated and exempt sales in Table 12?

Yes. Every outward supply belongs in the HSN summary, including nil-rated, exempt and zero-rated ones. Report the code, unit, quantity and taxable value as usual and leave the tax columns at zero.

What if my Table 12 total does not match the invoice tables?

The difference almost always comes from lines with a missing HSN code, a discount or rounding adjustment applied at the bill level rather than the line level, or credit notes handled inconsistently. Fix it in the source data and regenerate the summary. Overwriting the figure to force a match leaves your records and your return telling two different stories.

Can I report more HSN digits than required?

Yes, and it is usually the better choice. A 6 or 8 digit code already contains the shorter heading, so it satisfies a 4 digit requirement. Tagging items at 6 digits from the start also means you do not have to re-tag your catalogue if your turnover crosses Rs. 5 crore.

Does Table 12 apply to services too?

It does. Service supplies are reported in the same table using their SAC code. If your shop bills repairs, installation, delivery or annual maintenance, give each of those a SAC in the item master so they do not fall out of the summary.