GST doesn’t just care about what your invoice says — it cares about when you issue it. Issuing a tax invoice late can shift your time of supply, affect when tax is payable, and create compliance problems. The rules differ for goods and services.
Why timing matters: the “time of supply”
The invoice date is one of the anchors for the time of supply, which is the point at which GST becomes payable. Broadly, the time of supply is the earlier of:
- the date of the invoice (or the last date by which it should have been issued), and
- the date of receipt of payment (for goods, this payment trigger has been relaxed for most taxpayers; for services it still applies).
Because “the last date by which the invoice should have been issued” is built into the rule, issuing late doesn’t delay your tax — it can actually crystallise your liability earlier than the (late) invoice date.
Time limit for goods
For goods, the invoice must be issued:
- Before or at the time of removal of the goods for supply to the recipient, where the supply involves movement; or
- Before or at the time of delivery or making the goods available to the recipient, where there is no movement.
In other words, the invoice should travel with the goods (or precede them), not follow days later.
Time limit for services
For services, the tax invoice must be issued within 30 days from the date of supply of the service. For banking companies, financial institutions and NBFCs, this is extended to 45 days.
| Supply type | Time limit to issue invoice |
|---|---|
| Goods (with movement) | Before/at removal |
| Goods (no movement) | Before/at delivery |
| Services (general) | Within 30 days of supply |
| Services (banks/NBFCs/FIs) | Within 45 days of supply |
Continuous supply of services
Many services (subscriptions, retainers, maintenance contracts) are supplied continuously. Here the invoice timing depends on the contract:
- If the due date of payment is ascertainable from the contract → issue on or before that due date.
- If the due date is not ascertainable → issue on or before you receive payment.
- If payment is linked to an event/milestone → issue on or before that event is completed.
Advances and receipt vouchers
If you receive an advance for services before issuing the invoice, GST is generally payable on the advance at the time of receipt, and you issue a receipt voucher then. The tax invoice follows when the service is actually supplied. (For goods, advance-stage GST has been relaxed for most taxpayers.)
Special cases
- Reverse charge: where the recipient pays tax under RCM on supplies from an unregistered person, the recipient issues a self-invoice, and a payment voucher at the time of payment.
- Goods sent on approval / sale-or-return: the invoice is issued before or at the time the supply is confirmed, or within 6 months of removal, whichever is earlier.
Practical tips
- For goods, generate the invoice before the vehicle leaves — this also aligns with the e-way bill.
- For services, don’t let invoicing drift — the 30-day clock starts at supply, not at your convenience.
- For retainers and subscriptions, tie invoicing to the payment due dates in your contract.
- Issue receipt vouchers promptly for service advances.
The bottom line
Issue goods invoices before or at removal/delivery, and service invoices within 30 days (45 for banks/NBFCs). Because the time of supply uses the last date by which the invoice should have been issued, invoicing on time protects your tax position — late invoicing never buys you more time to pay.
For the full picture of GST timing, registration and returns, read the GST Guide for Small Businesses.