GST Invoice Compliance Checklist: Mandatory Fields and Common Errors

Your Invoice Is Your Customer’s Credit

A tax invoice is not a billing document that happens to show tax. It is the document on which your customer’s input tax credit depends, and one of the conditions for claiming credit is possession of a tax invoice or other prescribed document. A missing GSTIN, a wrong place of supply or an absent HSN code is therefore not a cosmetic error. It is a problem for the person you are trying to keep as a customer.

The mandatory particulars

Rule 46 prescribes what a tax invoice must contain. Broadly:

• Name, address and GSTIN of the supplier

• A consecutive serial number, unique for the financial year

• Date of issue

• Name, address and GSTIN or UIN of the recipient, where registered

• Name, address, and address of delivery with the State and code, for an unregistered recipient above the prescribed value

• HSN code for goods or SAC for services, to the required number of digits

• Description, quantity and unit

• Total value, taxable value after discount, rate and amount of tax under each head

• Place of supply with the State, for inter-state supply

• Address of delivery where different from the place of supply

• Whether tax is payable on reverse charge

• Signature or digital signature

When the invoice must be issued

Broadly, before or at the time of removal or delivery for goods, and within the prescribed period from the supply for services.

Timing matters because it feeds the time of supply, which decides which return the liability belongs in. See our article on time of supply.

Tax invoice against bill of supply

A bill of supply is issued where no tax is charged: by a composition dealer, or for exempt supplies. It carries no tax and gives the recipient no credit.

Issuing a bill of supply where a tax invoice was required, or the reverse, is a structural error rather than a clerical one.

Where e-invoicing applies

If you are covered by e-invoicing, the invoice is reported to an Invoice Registration Portal and the Invoice Reference Number and QR code must appear on the invoice issued to the customer. Without a valid IRN the document is not a valid tax invoice.

See our articles on e-invoicing applicability and e-invoice registration.

The errors that actually cause trouble

Wrong or missing customer GSTIN. The supply does not reach the right GSTR-2B, and the customer has no credit.

Wrong place of supply. CGST and SGST charged where IGST was due, or the reverse. Correcting the head is harder than correcting a value.

Serial numbering that breaks or repeats. The series has to be consecutive and unique for the year, and Table 13 of GSTR-1 reports the document series.

HSN or SAC wrong or missing, or at the wrong number of digits for your turnover.

Reverse charge not flagged where it applies.

Invoice raised after the goods moved, which creates an e-way bill problem as well as a timing one.

Discounts handled inconsistently between the invoice and the credit note position.

Build it into the system, not the review

Every one of those errors is preventable at the point the invoice is generated. Configure the item master with the right HSN, the customer master with the right GSTIN and state, and the series so it cannot repeat. Catching errors at month end means they have already gone to the customer.

How Northrop LLP helps

Northrop LLP reviews your invoice format against the prescribed particulars, fixes the masters that generate recurring errors, and reconciles your document series.