Reviewed by Finin2min Editorial Desk · Last reviewed 11 August 2026
Identify the likely tax date for forward-charge goods/services, reverse charge, vouchers and rate-change cases.
Determine likely time of supply
Continuous supply, associated enterprises, change in tax rate and excess advances can alter the result.
Likely time of supply
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Rule applied
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How This Is Calculated
Time of supply determines when GST liability arises — generally the earliest of the invoice date/due date for issuing the invoice, and the date of payment receipt, for goods and services under Sections 12 and 13 of the CGST Act. Different rules apply for specific situations like reverse charge, vouchers, or continuous supply, each with their own trigger dates.
Frequently Asked Questions
What determines the time of supply for goods?
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Generally the earlier of the invoice date (or the last date by which the invoice should have been issued) and the date payment is received — GST liability arises at this point, regardless of when the goods actually change hands.
Does the time of supply rule differ for reverse charge transactions?
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Yes. Under reverse charge, time of supply is determined differently — typically the earliest of the date of payment, or a specified number of days after the invoice date, reflecting that the recipient (not the supplier) is responsible for paying the tax.
Why does time of supply matter beyond just tax payment timing?
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It determines which tax period's return the transaction belongs in, which return rate/law version applies if rates changed, and determines the output-tax liability period; ITC eligibility and its outer deadline are governed separately, including section 16(4) for the recipient — getting the date wrong can shift a transaction into the wrong return period.
Source and review trail
Use the current official instrument, portal or regulator publication before acting.
Covered ordinary goods invoiced on the last permissible date, 20 October 2026, with an advance on 1 October have time of supply on 20 October. For ordinary RCM services, a 1 October document and 15 December payment give 1 December, the day immediately following 60 days. Historical voucher issue/redemption rules do not apply from 1 October 2025.
Sources checked 21 October 2026. The result applies only to the facts and scope stated above.
Recipient self-invoice branch from 1 November 2024
Where the recipient is required to invoice under section 31(3)(f), current section 13(3)(c) uses the recipient’s invoice date, with the earlier payment limb still applying. Do not substitute the supplier-document61-day limb for this case. Enter the actual self-invoice date; this calculator does not excuse late self-invoicing or calculate its separate consequences.
Scope: Determines the time of supply (the date on which GST liability arises) for goods and services, per Sections 12-13 of the CGST Act, to identify the correct tax period for reporting.
Calculation logic
For goods (forward charge): time of supply is the earlier of the date of issue of invoice (or the last date by which the invoice should have been issued under Section 31) and the date of receipt of payment.
For services (forward charge): time of supply is the earlier of the date of issue of invoice (if issued within the prescribed period under Section 31) or date of receipt of payment; if the invoice is not issued within the prescribed period, the earlier of the date of provision of service and date of receipt of payment.
For reverse charge supplies: time of supply is the earliest of the date of payment, or 30 days (goods) / 60 days (services) from the date of invoice issued by the supplier, with a residual rule (date of entry in the recipient's books) if neither of the preceding can be determined.
Inputs and assumptions
'Date of receipt of payment' for this purpose follows the earlier of the date entered in the recipient's books of account or the date credited to the recipient's bank account, per the statutory definition.
Time-of-supply rules applied follow the current CGST Act Sections 12-13; specific categories (e.g., vouchers, continuous supply of goods/services) have their own sub-rules within these sections, which the tool applies where that transaction type is selected.
Exclusions and edge cases
Determining the correct time of supply affects which tax period a transaction must be reported in and which rate applies if there has been a rate change — this tool identifies the applicable date, not the resulting rate itself (use the GST Calculator with the rate applicable as of that determined date).
Does not cover the separate 'change in rate of tax' rules under Section 14 (which govern which rate applies when supply straddles a rate-change date) — that is a related but distinct provision.