GST Time of Supply for Services: Invoice, Advance Payment and Reverse Charge Guide

For services under GST, the invoice date is important, but it is not always the date on which tax liability arises. Section 13 of the Central Goods and Services Tax Act, 2017 links the time of supply to events such as invoice issuance, receipt of payment and, in some cases, completion of the service. The correct sequence determines the tax period in which the liability should be recognised.

This guide focuses on ordinary taxable services, advances, late invoicing, reverse charge and continuous supply. The framework is in section 13 of the CGST Act on CBIC, while invoice timing is governed by section 31 and the prescribed invoice rules. CBIC's current Tax Information Portal text of section 31 is also useful for checking service-invoice and advance-receipt requirements.

The basic section 13 rule for services

For a normal taxable service, first ask whether the supplier issued the invoice within the period prescribed under section 31.

• Invoice issued within the prescribed period: time of supply is the earlier of the invoice date or receipt of payment.
• Invoice not issued within the prescribed period: time of supply is the earlier of the date the service was provided or receipt of payment.
• If neither rule determines the time: use the date on which the recipient records receipt of the service in its books.

For this rule, receipt of payment is the earlier of the date the payment is entered in the supplier's books or the date the amount is credited to the supplier's bank account. Month-end GST work therefore should not rely on invoice dates alone.

Why the invoice deadline changes the answer

Section 31 requires a tax invoice for taxable services within the prescribed period. CBIC's invoice rules page states that an ordinary taxable service invoice is generally issued within 30 days from the date of supply of the service. It provides a 45-day period for insurers, banking companies, financial institutions including non-banking financial companies, with special rules for specified cases.

If an invoice is timely, its date can be one of the competing events under section 13. If it is late, the late invoice date does not postpone the tax point; the comparison moves to service provision versus payment.

Two worked examples

Timely invoice: A consulting service is completed on 10 August. The invoice is issued on 20 August within the applicable period, and payment arrives on 15 September. Section 13 compares invoice and payment. The earlier event is 20 August, so that is the time of supply on these simplified facts.

Late invoice: The same service is completed on 10 August, but the invoice is issued only after the applicable prescribed period and payment is received later. Section 13 then compares service provision with payment. If payment was received after 10 August, the service date becomes the time of supply. A late invoice therefore does not automatically defer GST liability.

Advances for services can create an earlier tax point

Where a genuine advance is received as consideration for a taxable service, payment can become the earlier event under section 13. Section 31 also requires a registered person receiving an advance to issue a receipt voucher or another prescribed document. A deposit that is not treated as consideration does not become payment merely because cash has been received; its treatment depends on whether and when it is applied as consideration.

If a customer pays an advance on 5 August for a service to be performed in September, the payment event may fix the time of supply for that portion before performance or final invoicing. Finance teams should therefore maintain an advance register instead of relying only on the sales invoice ledger. CBIC's sectoral GST FAQs also explain section 13 treatment of advances and service payment timing.

Reverse charge has a separate timing rule

For services on which tax is payable under reverse charge, section 13 generally uses the earlier of:

• the date of payment as entered in the recipient's books or the date the recipient's bank account is debited, whichever is earlier; or
• the date immediately following 60 days from the supplier's invoice or other document.

If those tests do not determine the time, the fallback is the date of entry in the recipient's books. For a supply by an associated enterprise located outside India, section 13 uses the earlier of the recipient's book entry or payment date.

Continuous supply of services needs a contract check

Section 31 contains separate invoice triggers for continuous supply of services. If the payment due date is ascertainable from the contract, the invoice is issued on or before that due date. If it is not ascertainable, the invoice is issued before or at receipt of payment. If payment is linked to completion of an event, the invoice is issued on or before completion of that event.

For retainers, milestone contracts and annual maintenance arrangements, finance teams should therefore read contractual due dates and milestones before deciding whether the invoice was issued within the applicable framework.

Delayed-payment additions have their own timing

Section 13 provides that an addition to the value of supply arising from interest, late fee or penalty for delayed payment is taxed when the supplier receives that additional amount. Track it separately from the original invoice so it is not pushed into the wrong tax period.

Month-end decision checklist

1. Record the service event. Identify when the service was provided or the relevant contractual milestone.
2. Check invoice timeliness. Do not assume the invoice date controls unless it was issued within the applicable prescribed period.
3. Capture advances. Review bank receipts and advance ledgers for consideration received before invoicing or performance.
4. Use the statutory payment date. For the ordinary supplier-side rule, compare the supplier's book-entry date with bank credit.
5. Separate reverse-charge transactions. Apply the recipient-side payment test and 60-day trigger.
6. Review continuous supplies contract by contract. Due dates and milestones affect invoice timing.
7. Track delayed-payment additions separately. Interest, late fee and penalty have a receipt-based timing rule.
8. Check for a change in tax rate. Section 14 contains a separate rule when the rate changes; do not use the ordinary section 13 sequence without considering it.
9. Retain evidence. Preserve the contract, service-completion support, invoice, advance receipt, books, bank evidence and the tax-period reasoning.

Common mistakes

• Treating every invoice date as the time of supply without checking whether the invoice was timely.
• Ignoring advances because the final invoice has not yet been raised.
• Using a late invoice date even though section 13 moves the test to service provision versus payment.
• Applying the ordinary supplier rule to a reverse-charge service.
• Confusing a refundable deposit with consideration without checking whether it has been applied to the supply.
• Using place-of-supply rules to answer a time-of-supply question. Place of supply addresses jurisdiction; time of supply addresses when liability arises.

Practical takeaway

For GST on services, use a decision sequence rather than one date field. First decide whether the invoice was issued within the applicable period. Then compare the correct statutory events: invoice and payment for a timely invoice, service provision and payment for a late invoice, and a separate recipient-side sequence for reverse charge. Add advances, continuous-supply milestones and delayed-payment additions to the close process. That produces a more reliable tax-period conclusion than simply posting GST from the invoice date.