GST service invoices: applying the 30-day and 45-day limits under Rule 47

Which deadline controls the service invoice?

For an ordinary taxable service supplied by a registered person, Rule 47 generally requires the invoice within 30 days from the date of supply. The first proviso gives 45 days where the supplier is an insurer, banking company or financial institution, including an NBFC. A consultancy supplying a bank does not acquire the bank’s 45-day period: the proviso classifies the supplier. Special supplies and document rules must be checked before using either period.

Legal framework and the scope of this guide

Section 31(2) of the CGST Act permits a taxable-service invoice before or after provision of service, within the prescribed period. CBIC’s CGST Rules, Rule 47 states the ordinary and specified-supplier periods. The ICAI GST bare-law compilation, sections 13 and 31 and Rules 46–48 reproduces those rules alongside later provisions, including recipient self-invoicing under Rule 47A. This guide addresses ordinary supplier-issued taxable-service invoices during FY 2026–27. It does not use the supplier’s invoice window as a universal deadline for every GST document.

Establish the supply date before adding days

Keep the contract, work-completion evidence and service-delivery records together. A customer’s internal purchase-order closure or later payment approval is not automatically a fresh date of supply. Where services are continuous, milestones or contractual payment obligations matter: section 31(5) has specific invoice rules. Identify those cases first, rather than applying a generic completion-plus-30 calculation. Advance receipts, cessation of service and notified categories also need their own analysis.

The examples below concern single, completed taxable services, with the date of supply accepted on the stated facts. They exclude continuous-supply and distinct-person concessions, recipient self-invoicing, advances and any special extension. Day counts exclude the starting date and include the last day; they use calendar days, not a count of the supplier’s working days. The examples assert no automatic holiday extension. Operationally, issue earlier rather than building a billing process around the last permissible day.

The 45-day period belongs to specified suppliers

Verify the supplier’s legal character rather than its customer list or marketing description. An ordinary accounting firm, software consultant or other service provider normally remains in the 30-day branch even where its client is a bank. Conversely, a qualifying banking-company supplier falls within the first proviso for its taxable service. The longer period does not convert exempt services into taxable services; first establish whether a tax invoice is required at all.

Distinct persons and other exceptions need separate routing

The second proviso to Rule 47 concerns the specified insurer, bank, financial institution including NBFC, telecom operator or notified class supplying taxable services between distinct persons under section 25. It permits invoicing before or at book recording, or before expiry of the quarter in which the supply was made. This is a defined supplier-and-relationship concession. It is not a quarterly billing option for every interbranch service. Document the exact proviso and its conditions before relying on it.

A recipient issuing its own reverse-charge invoice under section 31(3)(f) follows Rule 47A’s separate receipt-based rule, not the supplier deadline discussed here. Exempt supplies generally call for a bill of supply under section 31(3)(c). E-invoice requirements, where applicable, remain a separate validity and reporting check; meeting a calendar deadline does not by itself prove that a compliant invoice was issued.

Late invoicing can change the time-of-supply analysis

Under section 13(2), timely invoicing ordinarily brings the earlier of invoice date and payment receipt into the time-of-supply test. Where the invoice is late, the provision-of-service date and payment receipt become relevant under clause (b). Consequently, postponing invoice issue does not safely postpone tax liability. A late invoice review should compare the service evidence, invoice, payment records and relevant return period. Do not backdate a document to conceal a delay or assume that a customer’s later accounting entry corrects it.

A useful billing control is an ageing register with separate columns for supply date, applicable rule, calculated last date, actual issue date, valid document reference and unresolved tax-period consequences. Escalate missing completion evidence as well as invoices nearing their deadline; an attractive ageing report built on an unsupported start date gives false assurance.

Six worked illustrations

All facts and amounts below are fictional. Assumptions describe the model, not additional statutory rules.

Illustrative example 1: Ordinary supplier, 30 days

A registered consultancy completes a single taxable service on 10 April 2026. Under the stated ordinary-rule assumptions, 10 April plus 30 calendar days is 10 May 2026. An invoice issued on 10 May falls on the model’s last day.

Illustrative example 2: Specified supplier, 45 days

A banking company supplies a taxable service on 10 April 2026. The first proviso applies on the assumed facts. Adding 45 days gives 25 May 2026, which is 15 days later than the ordinary 30-day result. Being the bank’s customer would not give a consultant this extension.

Illustrative example 3: Month-end supply

An ordinary registered service supplier provides a single service on 31 August 2026. Adding 30 calendar days produces 30 September 2026. Counting only working days would produce a different and unsupported deadline for this illustration.

Illustrative example 4: Invoice issued after the ordinary limit

The ordinary service date is 10 April 2026 and actual issue is 12 May 2026. The elapsed interval is 32 days, so issue is 2 days beyond the 10 May limit. The supplier must separately examine section 13 rather than assume 12 May controls the tax period.

Illustrative example 5: Cross-month 45-day computation

A qualifying financial-institution supplier provides its taxable service on 1 May 2026. The 45-day interval ends on 15 June 2026. A diary entry for 30 June would exceed that calculated deadline by 15 days.

Illustrative example 6: One billing run, two supplies

An ordinary supplier completes independent services on 10 April and 20 April 2026. Their 30-day limits are 10 May and 20 May. A billing run issuing the respective invoices on 15 May is 5 days late for the first and 5 days before the second deadline. A common run date does not merge their statutory clocks.

Ten-step verification table

Step	Action	Evidence
1	Identify the document	Supplier tax invoice, bill of supply or recipient self-invoice.
2	Establish registration and taxability	GSTIN and supply classification record.
3	Evidence the supply date	Contract, deliverable and completion records.
4	Screen special supplies	Continuous supply, advances, cessation and notified provisions.
5	Classify the supplier	Evidence supporting ordinary or financial-sector status.
6	Test distinct-person concession	Section 25 relationship and second-proviso supplier eligibility.
7	Calculate the last date	Calendar-day working paper and rule reference.
8	Verify actual issue	Issued document and applicable e-invoice validation evidence.
9	Review tax-period consequences	Section 13 analysis using invoice, service and payment dates.
10	Close ageing exceptions	Correction trail, escalation and reconciled billing register.

Sixteen practitioner FAQs

1. Does Rule 47 cover goods invoices?

Its ordinary 30-day and 45-day periods concern taxable services. Goods have different section 31 timing rules.

2. Can a supplier invoice before completion?

Section 31(2) permits issue before or after provision within the framework. Advance and time-of-supply consequences must still be assessed.

3. Does a bank customer get 45 days?

No. The first proviso identifies the supplier’s status, not its recipient’s.

4. Does every finance-related consultant qualify?

No. A service description involving finance does not itself make the supplier a banking company or financial institution.

5. Is an NBFC expressly included?

Yes, the first proviso includes a non-banking financial company within its stated financial-institution category.

6. Are the examples business-day calculations?

No. They use calendar-day intervals with the start date excluded.

7. Can the buyer’s approval date replace service completion?

Not automatically. Determine the legally relevant facts and any specific contractual continuous-supply rules.

8. Is quarterly invoicing available to every branch?

No. The second proviso has both specified-supplier and distinct-person conditions.

9. Does an interbranch supply necessarily satisfy those conditions?

No. Verify distinct-person status under section 25 and the supplier class as well as the proviso’s timing language.

10. What changes for continuous services?

Section 31(5) has specific rules linked to the contract and payment or completion events. Route such cases for separate review.

11. What about reverse-charge self-invoices?

Recipient invoices under section 31(3)(f) are governed by Rule 47A’s separate rule, including its receipt-based trigger.

12. Does an exempt service need a Rule 47 tax invoice?

Normally the section 31(3)(c) bill-of-supply framework applies. Confirm the supplier and supply treatment.

13. Does timely preparation in accounting software prove issue?

No. Retain the actual issued document and evidence of compliance with the applicable manner of issuing it.

14. Can a late invoice defer tax automatically?

No. Section 13(2)(b) changes the relevant time-of-supply test where invoicing is outside the prescribed period.

15. Should an overdue invoice be backdated?

No. Preserve truthful issue records and analyse the correct tax and reporting consequences.

16. What should the monthly review reconcile?

Completion records, invoice ageing, actual issue dates, receipts and the tax-period analysis, with unresolved exceptions assigned to an owner.

Conclusion

Ordinary taxable service invoices generally follow Rule 47’s 30-day limit; specified financial-sector suppliers have 45 days. Classify the supplier and supply before calculating the deadline, and review time of supply separately.