Why time of supply matters
GST liability is tied to a statutory point in time. Sections 12 and 13 set the core rules for goods and services, while Section 14 deals with a change in the rate of tax. The document date alone does not always answer the question.
Goods on forward charge
For ordinary goods, Section 12(2) uses the earlier of the invoice or required-invoice date and the date the supplier receives payment. Record both dates before choosing the tax point.
Reverse charge for goods and services
Reverse-charge goods consider receipt, payment and the date immediately following 30 days from the supplier invoice, with a books-entry fallback. Reverse-charge services use payment or the date immediately following 60 days from the supplier invoice, with a specific overseas associated-enterprise proviso.
Services, vouchers and rate changes
Forward-charge services change depending on whether the invoice was issued within the prescribed period. Vouchers use issue date when the supply is identifiable then; otherwise redemption date applies.
When a GST rate changes, Section 14 compares the supply date with the rate-change date and then tests invoice and payment dates. These combinations can produce a different tax point from a standard shortcut.
A practical date-check workflow
Start with the transaction type, gather only the dates used by the applicable section, run the comparison, and save the result with the rule applied.
Use the GST Time of Supply Calculator, then verify special facts, notifications and the applicable HSN/SAC rate before filing or reporting.
Primary source: CBIC — CGST Act, Sections 12–14.
Open the GST Time of Supply Calculator →Frequently asked questions
Does payment always decide the GST tax point?
No. The applicable section may use invoice, supply, receipt, books entry or a combination of dates.
Is the reverse-charge invoice limb exactly 30 days after the invoice?
The Act says the date immediately following thirty days from the invoice date for goods and immediately following sixty days for services.
Does Section 14 matter when GST rates change?
Yes. Section 14 contains specific combinations for supplies before or after a rate change.
Can this guide determine the applicable GST rate?
No. Classification and rate notifications must be checked separately.