What does section 15 regulate?

It regulates value of taxable supply. Read the exact text, conditions, exceptions and transaction date together.

Which subordinate law should be checked?

Rule 27, Rule 28, Rule 29, Rule 30, Rule 31, Rule 31A, Rule 31B, Rule 31C, Rule 31D, Rule 32, Rule 33, Rule 34. Notifications, circulars, forms and the corresponding SGST/UTGST layer may also apply.

What evidence should be retained?

Preserve the contract or transaction record, invoice or form, portal acknowledgement, payment/ledger evidence, correspondence, legal working and the official source version used.

Can portal behaviour override the statute?

No. Portal functionality is operational evidence; legal entitlement and liability remain controlled by the Act, Rules, notifications and binding decisions.

Which GST rate applies when the rate changes between invoice and payment?

Fix the transaction date first, then follow the applicable rate/exemption notification chain. GST rates are effective-date driven, not timeless slabs.

When does GST become payable on this transaction?

Apply section 15 to the exact facts and period, then verify the linked delegated law and official implementation material before concluding.

What amount should be treated as taxable value?

Apply section 15 to the exact facts and period, then verify the linked delegated law and official implementation material before concluding.

Does an advance change the GST tax period?

Apply section 15 to the exact facts and period, then verify the linked delegated law and official implementation material before concluding.

Section 15 - Value of taxable supply

Reviewed by CA Nikhil Gupta and Kajri Singh · Last reviewed 30 August 2026

Chapter IV - Time and Value of Supply

ACTIVE

Official source: The controlling wording and amendment notes are maintained by India Code and CBIC. Open consolidated Act PDF.

Finin2min Summary - Section in 2 Minutes

Starts with transaction value for unrelated parties and sole consideration, then adds statutory inclusions, discount conditions and valuation rules. Non-GST taxes and supplier liabilities borne by recipient are included. Incidental expenses and pre-delivery activities charged by supplier are included. Delayed-payment interest/late fee/penalty is included on receipt. Price-linked non-government subsidy is included. Post-supply discount requires pre-existing agreement, invoice linkage and recipient ITC reversal. Related/distinct-person and notified supplies move to rules 27-35/31B-31D.

Provision position

Present in current consolidated Act

CGST chapter

Chapter IV — Time and Value of Supply

Legal source control

India Code + CBIC official repositories

Law checked

27 July 2026

How to use this page: Application remains transaction-date sensitive: check commencement, amendment history, Rules, notifications and State/UT overlay before reliance. The official consolidated Act controls the statutory wording; the Finin2min layers explain how to apply and evidence it.

Future-law control — do not apply yet

Section 15(3)(b) — Finance Act 2026 section 153: Substitution relating to post-supply discount conditions. Status: Enacted (not yet operative); commencement: Yet to be notified. CBIC source.

Why Section 15 matters

Section 15 (Value of taxable supply) is the section-level control point within Chapter IV — Time and Value of Supply. Time and value decide when GST becomes payable and on what amount. These provisions become especially important when invoice, payment, supply or rate-change dates do not align.

Current-law and amendment control

validation 1 — controlling consolidated Act

India Code — Central Goods and Services Tax Act, 2017. Used for the current chapter/section inventory and consolidated provision status.

validation 2 — independent official cross-check

CBIC Tax Information Portal. Use the Act HTML/PDF and amendment history together with current notifications/circulars.

Transaction-date rule: Never treat today’s consolidated wording, a portal screen or an enacted-but-uncommenced amendment as proof of the law that applied on another date. Fix the relevant tax period first.

Official statutory text

The authoritative provision, footnotes and amendment notes are maintained in the official consolidated Act. This analytical page does not re-typeset amendment markers into the running statutory sentence.

Official-source reference reviewed on 2026-07-28. Apply the version and commencement position relevant to the transaction period.

Clause-by-clause / paragraph-wise decode

Section–Rule–Form–Notification–Circular bridge

Rule 27 Rule 28 Rule 29 Rule 30 Rule 31 Rule 31A Rule 31B Rule 31C Rule 31D Rule 32 Rule 33 Rule 34 Rule 35

The mapping is a legal concordance, not a round-robin related-link list. It is limited to instruments listed in this repository.

Practical example

A customer pays a statutory fee that the supplier was contractually liable to bear. The amount is added to value even if paid directly to the authority. PROFESSIONAL ALERT Commercial credit notes do not automatically reduce GST value.

F2 Finin2min · Finance & Law Explained in 2 Minutes GST BARE ACT & RULES SERIES · CHAPTER V CGST Act, 2017 Input Tax Credit ITC conditions, blocked credits, reversals, special circumstances, job work, mandatory ISD distribution and recovery. Legal cut-off: 28 June 2026 India Code Act: as on 11 June 2026 Sections 16, 17, 18, 19, 20, 21 Edition GST26

Legal snapshot Decision flow Act sections Rules Notifications & circulars Cases Q&A Sources

Legal snapshot ACT COVERAGE CGST Act sections 16-21 6 statutory provisions. RULES COVERAGE 12 Rules mapped in the chapter with official active-rule links and amendment controls. REPOSITORY LAYER 9 case studies · 15 Q&A Official sources, examples, alerts and cheat framework. Legal control: The current Act source is the India Code consolidation marked as on 11 June 2026. Rules are controlled through active CBIC pages and Gazette instruments up to 28 June 2026; the official 1 June 2021 compilation is used only as a stable full-text base where no later material amendment affects the rule. The Gazette and applicable State law prevail. Senior finance & tax decision flow 1 Confirm registered person and business nexus ↓ 2 Verify tax document and GSTR-2B ↓ 3 Prove receipt and tax/return conditions ↓ 4 Test section 17(5) blocks ↓ 5 Allocate taxable/exempt and business/non-business use ↓ 6 Track 180-day payment ↓ 7 Apply November/annual-return time limit

↓ 8 Process special stock/job-work/ISD rules ↓ 9 Reconcile books, 2B, 3B and vendor compliance Act - paragraph-by-paragraph The statutory text is followed by a practical interpretation layer. Examples illustrate application; they do not replace transaction-specific facts or binding law.

Professional alert

Confirm the transaction-date amendment and commencement position before reliance.

Finin2min decision path

Fix the supply date, invoice date and payment date.
Apply the correct goods/services time-of-supply rule.
If the rate changed, test the statutory rate-change rule using the exact dates.
Determine taxable value and prescribed adjustments.
Reconcile the result to invoice and return reporting.

Practical case studies

Case 1 — Section-specific application — A taxpayer encounters an issue involving value of taxable supply. The working paper should identify the exact subsection/proviso, linked Rule/Form/instrument, tax period and evidence before recording the conclusion.

Case 2 — Invoice, payment and supply fall on opposite sides of a rate change. Use the statutory time/rate-change sequence rather than the date most convenient to the ERP.

Case 3 — Related entities transact at a value that needs a prescribed valuation test. Document the relationship, consideration and applicable valuation rule.

Accounting, ERP & portal touchpoints

ERP design should retain supply, invoice, payment and rate-effective dates separately; one posting date is not enough for GST timing analysis.

Control: keep the legal conclusion separate from system configuration; document every tax-code/master change and its effective date.

Notice, litigation & evidence risk

Wrong tax point or value can create interest, recipient ITC mismatch and rate disputes. Preserve price terms, payment evidence and rate-notification versions.

Evidence hierarchy: source transaction → books/ERP → statutory return/form → portal acknowledgement → legal working → correspondence/order.

Judicial position — how to read precedent

Start with binding Supreme Court authority, then the jurisdictional High Court, other High Courts and GSTAT where applicable. AAR/AAAR rulings are fact- and jurisdiction-sensitive and should not be presented as universal law. Always check whether a decision has been stayed, reviewed, distinguished or overtaken by amendment.

Open the Finin2min provision citator · Open the connected GST case-law module

Common mistakes to avoid

Using invoice date as the universal time of supply.
Applying today’s rate to a past transaction.
Ignoring non-monetary or related-party valuation rules.
Changing ERP tax codes without preserving the effective-date trail.

Questions professionals actually ask

Which GST rate applies when the rate changes between invoice and payment?: Fix the transaction date first, then follow the applicable rate/exemption notification chain. GST rates are effective-date driven, not timeless slabs.
When does GST become payable on this transaction?: Apply section 15 to the exact facts and period, then verify the linked delegated law and official implementation material before concluding.
What amount should be treated as taxable value?: Apply section 15 to the exact facts and period, then verify the linked delegated law and official implementation material before concluding.
Does an advance change the GST tax period?: Apply section 15 to the exact facts and period, then verify the linked delegated law and official implementation material before concluding.

Related law and practical resources

Chapter IV guide Practical GST pathways CGST Rules GST Forms Notifications Circulars Provision citator Case law GST Portal controls State/UT overlays

Finin2min takeaway: Section 15 should never be applied alone. Read the exact provision, the connected Rules/forms/instruments, the transaction date, the State/UT overlay and the binding judicial position together.

Implementation checklist

Fix the transaction, taxable period and jurisdiction.
Read every subsection, proviso, explanation and omission marker.
Open the mapped Rule, form, notification and circular.
Test State/UT variation and portal version.
Preserve evidence, approvals, working papers and acknowledgements.
Record the conclusion, assumptions, source date and reviewer.

Evidence and retention checklist

Contract, purchase order, invoice or underlying transaction document.
Registration, return, ledger, challan and portal acknowledgement.
Official Act/Rule/notification version used and effective date.
Internal tax position paper, computation and management approval.
Correspondence, notices, replies, orders and appeal papers where applicable.

Practical Q&A

What does section 15 regulate?: It regulates value of taxable supply. Read the exact text, conditions, exceptions and transaction date together.
Which subordinate law should be checked?: Rule 27, Rule 28, Rule 29, Rule 30, Rule 31, Rule 31A, Rule 31B, Rule 31C, Rule 31D, Rule 32, Rule 33, Rule 34. Notifications, circulars, forms and the corresponding SGST/UTGST layer may also apply.
What evidence should be retained?: Preserve the contract or transaction record, invoice or form, portal acknowledgement, payment/ledger evidence, correspondence, legal working and the official source version used.
Can portal behaviour override the statute?: No. Portal functionality is operational evidence; legal entitlement and liability remain controlled by the Act, Rules, notifications and binding decisions.

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