When you purchase goods or services liable to reverse charge mechanism (RCM) from an unregistered vendor, the vendor cannot issue a GST tax invoice. The statutory burden shifts to you as the recipient. You must document the transaction, pay the tax directly in cash in your GSTR-3B return, and claim eligible input tax credit (ITC) based on your self-invoice.
The 30-day rule under Rule 47A
Before November 2024, the law stated that an invoice must be issued on the date of receipt of goods or services from an unregistered person. This strict same-day requirement caused compliance difficulties for businesses during monthly accounting closes.
Effective 1 November 2024, Notification No. 20/2024-Central Tax inserted Rule 47A into the CGST Rules. The rule gives recipients a specific timeline: where an invoice referred to in Rule 46 is required to be issued under clause (f) of sub-section (3) of section 31 by a registered person liable to pay tax under Section 9(3) or Section 9(4), the recipient shall issue the invoice within a period of thirty days from the date of receipt of the supply of goods or services or both.
Common mistake: Waiting until the end of the financial year or annual audit to generate self-invoices. If you delay self-invoicing beyond 30 days from the receipt of supply, you breach Rule 47A and lack valid documentation under Rule 36(1)(b) to support your input tax credit claim.
Section 31(3)(f) self-invoice format and requirements
Under Section 31(3)(f) of the CGST Act and Rule 36(1)(b) of the CGST Rules, an invoice issued by the recipient is an eligible document for claiming input tax credit. The document must contain the standard particulars required under Rule 46 of the CGST Rules:
- Consecutive serial number: A unique invoice number containing only alphabets, numerals, and special characters (hyphen or dash, slash), unique for a financial year.
- Date of issue: Must fall within 30 days of receiving the supply as prescribed in Rule 47A.
- Recipient details: Your company name, address, and GSTIN.
- Supplier details: Name and address of the unregistered supplier.
- Description of supply: Description of goods or services, HSN or SAC code, quantity, and total value.
- Tax breakdown: Taxable value, applicable GST rate, and the exact amounts of CGST, SGST, or IGST.
- Reverse charge declaration: A prominent note specifying that tax is payable on reverse charge.
According to official guidance on the e-Invoice Portal FAQ, e-invoicing does not apply to invoices issued by the recipient on receipt of supplies under reverse charge from unregistered persons under Section 9(4) or Section 31(3)(f). You do not need to generate an Invoice Reference Number (IRN) for self-invoices.
Payment voucher under Section 31(3)(g)
In addition to the self-invoice, the law requires a separate document when paying the vendor. Under Section 31(3)(g) of the CGST Act, a registered person liable to pay tax under Section 9(3) or Section 9(4) shall issue a payment voucher at the time of making payment to the supplier.
While the self-invoice records the purchase and forms the base for your ITC claim, the payment voucher records the monetary settlement with the unregistered vendor. Both documents must be retained in your records for audit and departmental scrutiny.
Worked example: unregistered legal services
Consider an enterprise, ABC Manufacturing Ltd in Maharashtra, that engages an unregistered individual advocate for a legal opinion. The advocate delivers the final legal opinion on 10 November 2026 and submits a professional fee bill of ₹50,000. Legal services by an individual advocate are subject to RCM under Section 9(3) at 18% GST (9% CGST and 9% SGST). ABC Manufacturing Ltd settles the advocate's fee on 25 November 2026.
| Compliance step | Statutory reference | Due date / Action date | Value and tax breakdown |
|---|---|---|---|
| Receipt of supply | Section 9(3) | 10 November 2026 | Fee: ₹50,000 |
| Issue self-invoice | Section 31(3)(f) and Rule 47A | Issued on 18 November 2026 (within 30 days) | Taxable value: ₹50,000; CGST 9%: ₹4,500; SGST 9%: ₹4,500; Total tax: ₹9,000 |
| Issue payment voucher | Section 31(3)(g) | Issued on 25 November 2026 (at payment time) | Disbursement: ₹50,000 |
| GSTR-3B return filing | Table 3.1(d) & Table 4(A)(3) | Filing for November 2026 | Cash tax paid: ₹9,000; Eligible ITC claimed: ₹9,000 |
The math is straightforward:
Taxable value = ₹50,000
CGST (9%) = ₹50,000 × 9% = ₹4,500
SGST (9%) = ₹50,000 × 9% = ₹4,500
Total RCM liability = ₹4,500 + ₹4,500 = ₹9,000
ABC Manufacturing Ltd reports ₹9,000 under Table 3.1(d) of Form GSTR-3B and discharges the entire liability using its electronic cash ledger. It simultaneously claims ₹9,000 as input tax credit in Table 4(A)(3) of Form GSTR-3B. Because the supplier is unregistered, this transaction does not appear in GSTR-2B. To see how RCM invoices are handled alongside auto-populated supplier data, read our detailed guide on RCM invoices and GSTR-2B Table 4 matching.
Frequently asked questions
What is the time limit to issue an RCM self invoice?
Under Rule 47A of the CGST Rules, inserted by Notification No. 20/2024-Central Tax, the recipient must issue the self-invoice within a period of thirty days from the date of receipt of the supply of goods or services or both.
Does an RCM self-invoice require an e-invoice IRN?
No. Inward supplies liable to reverse charge received from unregistered persons where the recipient issues a self-invoice under Section 31(3)(f) do not require an Invoice Reference Number (IRN).
When must a payment voucher be issued under RCM?
Under Section 31(3)(g) of the CGST Act, a registered person liable to pay tax under reverse charge must issue a payment voucher at the time of making payment to the supplier.
Check your own GSTR-2B
Separate inward supplies from unregistered vendors from registered supplier data automatically. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.
Last checked: 25 October 2026. Sources: Notification No. 20/2024-Central Tax, CBIC Section 31 CGST Act, e-Invoice Portal FAQ.