Time of Supply Under GST: When Tax Is Due on Goods, Services and RCM

The short answer

Time of supply is the date on which the GST liability arises. It decides the month in which a sale is reported in GSTR-1 and the tax is paid in GSTR-3B. Section 12 of the CGST Act covers goods, Section 13 covers services, and Section 14 covers a change in the tax rate. In practice:

• Goods: the invoice date (the invoice must be issued on or before removal or delivery).
• Services: the invoice date or the payment date, whichever is earlier — if the invoice is issued within 30 days.
• Reverse charge: a date on the buyer's side — usually the payment date, with a 30-day (goods) or 60-day (services) backstop.

Time of supply of goods (Section 12)

The law says the time of supply of goods is the earlier of (a) the date of the invoice, or the last date by which the invoice should have been issued under Section 31(1), and (b) the date of receipt of payment.

Two things simplify this in practice:

• The invoice is issued at removal. Under Section 31(1), a tax invoice for goods must be issued before or at the time of removal for supply (when the goods move) or delivery / making available (when they don't). So the "last date for the invoice" is the day the goods leave.
• No GST on advances for goods. Notification 66/2017-Central Tax (15 November 2017) says registered persons need not pay GST on advances received for goods; tax is paid when the invoice is issued. Composition taxpayers were covered earlier by Notification 40/2017-Central Tax.

Example: a trader in Kochi receives an advance of ₹50,000 on 28 September for goods dispatched on 3 October with an invoice dated 3 October. No tax on the advance; the sale goes into the October GSTR-1 and GSTR-3B.

Time of supply of services (Section 13)

For services, everything depends on whether the invoice was issued on time. Rule 47 gives 30 days from the date the service is supplied (45 days for banks, insurers and NBFCs).

Situation	Time of supply
Invoice issued within 30 days	Invoice date or payment date, whichever is earlier
Invoice issued late (after 30 days)	Date the service was provided or payment date, whichever is earlier
Neither of the above can be applied	The date the recipient records the service in its books

Payment date means the earlier of the date the payment is entered in your books and the date it is credited to your bank account.

Example 1 — on time: a consultant finishes a job on 10 October and issues the invoice on 2 November; the client pays on 15 November. The invoice was within 30 days, so the time of supply is 2 November → November returns.

Example 2 — late invoice: same job, but the invoice is issued on 20 November (41 days later). The invoice is late, so the time of supply goes back to the service date, 10 October → October returns, and interest under Section 50 if the tax was paid late.

Advances for services

Unlike goods, an advance for services does create a tax liability on the date you receive it. Issue a receipt voucher (Rule 50), report the advance in GSTR-1 Table 11A and pay the tax in that month's GSTR-3B. When the invoice is issued later, adjust the advance in Table 11B so the tax is not paid twice. If you receive up to ₹1,000 more than the invoice value, you may treat the invoice date as the time of supply for that small excess.

Reverse charge: the buyer's date (Sections 12(3) and 13(3))

Under reverse charge the recipient pays the tax, so the clock runs on the recipient's side:

RCM on	Time of supply — the earliest of
Goods	Date of receipt of goods · date of payment · the day after 30 days from the supplier's invoice date
Services	Date of payment · the day after 60 days from the supplier's invoice date

If none of these can be determined, it is the date of entry in the recipient's books. For services from an associated enterprise outside India, it is the date of entry in the books or the payment date, whichever is earlier. RCM tax is shown in GSTR-3B Table 3.1(d) and always paid in cash.

Example: a registered company pays a legal fee of ₹30,000 to an advocate firm (RCM) on 5 December against an invoice dated 1 October. The 60-day backstop ends first (the day after 60 days is 1 December), so the time of supply is 1 December.

When the tax rate changes (Section 14)

When a rate changes in the middle of a deal — as happened when GST 2.0 rates took effect on 22 September 2025 — Section 14 looks at three events: the supply, the invoice and the payment. Whichever two of them fall on the same side of the change decide the rate.

Supply	Invoice	Payment	Time of supply
Before	After	After	Earlier of invoice and payment (new rate)
Before	Before	After	Invoice date (old rate)
Before	After	Before	Payment date (old rate)
After	Before	After	Payment date (new rate)
After	Before	Before	Earlier of invoice and payment (old rate)
After	After	Before	Invoice date (new rate)

For this rule, the payment date is the date it is credited to the bank, if that happens more than four working days after the change.

Vouchers and continuous supplies

• Vouchers (gift cards, coupons): the date of issue if the supply is identifiable then; otherwise the date of redemption.
• Continuous supply (electricity, telecom, subscriptions with periodic billing): the invoice is due on or before the due date of each payment, or when each payment is received if no due date is fixed (Section 31(4) and (5)).

Common mistakes

• Charging GST on an advance for goods. It has not been needed since 15 November 2017.
• Forgetting tax on an advance for services. The receipt voucher and Table 11A are compulsory.
• Raising service invoices late. After 30 days the time of supply jumps back to the service date — and the return for that month may already be filed.
• Waiting for the supplier under RCM. The 30/60-day backstop applies even if you have not paid.
• Dating the invoice after the goods leave. The invoice must go with or before the goods, and the e-way bill quotes it.

Practise it before you do it for real

On IndIaTaxSim, a safe copy of the GST portal, you raise invoices with your own dates, report advances in GSTR-1 Table 11A/11B, pay RCM in GSTR-3B 3.1(d) and see which month each one lands in. Modules 5, 10–15 and 19 of the GST Portal Walkthrough cover invoices, GSTR-1, GSTR-3B and RCM, and the GST Practice Lab walks one family business through the same steps month by month.