GST Invoice Format for Service Providers: What a Valid Invoice Must Show

Who needs to issue a GST tax invoice

If you are registered for GST and supply taxable services, you issue a tax invoice and charge GST. If you are not registered, you cannot charge GST, and your document should not look like a tax invoice. A business under the composition scheme issues a bill of supply instead. Which one applies to you depends on your registration, so confirm with your accountant.

Fields a GST invoice for services should show

Rule 46 of the CGST Rules lists the particulars of a tax invoice. For a typical service invoice, they come down to the following.

• Your name, address and GSTIN.
• A consecutive invoice number of up to 16 characters, using letters, numbers, a hyphen or a slash, unique for the financial year.
• The date of the invoice.
• The client's name and address, and their GSTIN if they are registered.
• The description of the service, with its SAC (Services Accounting Code).
• Quantity or unit where relevant, and the value of the service before tax.
• Any discount, and the taxable value after it.
• The rate and amount of CGST and SGST, or IGST, charged.
• The place of supply, with the state name and code when the supply is to another state.
• Whether tax is payable on reverse charge.
• Your signature or digital signature.

Practical tipIf the client is unregistered and the taxable value is ₹50,000 or more, the invoice also needs their name and address, and the state name and code. Below that, those details are needed only if the client asks.

CGST and SGST, or IGST?

Look at where you are and where the place of supply is. When both are in the same state, the tax is split into CGST and SGST, each at half the GST rate. When the place of supply is in a different state, the whole rate is charged as IGST. For most services the place of supply is the client's location if they are registered, but there are exceptions, so check the rule for your kind of service.

Example: an 18% service of ₹10,000 supplied within one state shows CGST 9% (₹900) and SGST 9% (₹900), a total of ₹11,800. Supplied to another state, it shows IGST 18% (₹1,800), also ₹11,800.

A simple layout to follow

Put the document title “Tax Invoice” at the top, your details on the left, and the invoice number and date on the right. Below, show the client's details and the place of supply, then a table: description, SAC, quantity, rate, taxable value, tax rate and tax amount. Finish with the totals, the amount in words, the payment details and the signature block.

Keep payment terms short and visible, such as “Due within 7 days; UPI: name@bank”. A clear due date is also what makes a payment reminder easy later.

Mistakes that cause problems

Most invoice corrections come from a handful of avoidable errors.

• Duplicate or skipped invoice numbers, or numbers that restart in the middle of the financial year.
• Missing SAC codes or the wrong tax rate for the service.
• The wrong tax split because the place of supply was assumed.
• A client GSTIN with a typo, which can stop them claiming credit.
• Retyping the quotation into the invoice and changing a figure by accident.

Turnover-based rules to check separately

Some requirements depend on your annual turnover, such as how many digits of the HSN or SAC code must be reported in returns, and whether you must generate e-invoices through the government portal. These thresholds have changed over time, so check the current rules on the GST portal or with your accountant rather than relying on an older article.

Keep the quotation and invoice connected

Retyping a quotation into an invoice template is where numbers drift. WTS CRM builds the GST invoice from the same line items as the accepted quotation, works out CGST and SGST or IGST from the place of supply, and records part payments against it. It creates and tracks invoices; it is not accounting software, so returns and bookkeeping stay with your accountant.