Rule 46 of the CGST Rules lists the mandatory fields of a GST tax invoice: supplier name, address and GSTIN; a unique serial number up to 16 characters; date; recipient details; HSN/SAC; description; quantity and unit; total and taxable value; tax rate and amount by tax head; place of supply for inter-state sales; delivery address if different; reverse charge status; signature; and a QR code with IRN for e-invoices.
Every GST tax invoice must carry a fixed list of particulars. That list sits in Rule 46 of the CGST Rules, 2017, and it is the yardstick a tax officer, an auditor and your buyer's accounts team will use to judge your bill.
This article goes through Rule 46 clause by clause, explains when each field applies, and ends with a checklist you can run on any invoice. For how to arrange these fields on a page, read GST invoice format instead.
Why do mandatory fields matter?
Three reasons. First, Section 31 requires a registered person to issue a tax invoice with "such particulars as may be prescribed", so an invoice missing a particular is not fully compliant. Second, your registered buyer relies on the invoice to claim input tax credit, so defects travel downstream and damage the relationship. Third, the same fields feed your GSTR-1, and a wrong GSTIN or value there shows up as a mismatch in the buyer's GSTR-2B.
The 17 mandatory fields of Rule 46, clause by clause
| Clause | Field | Applies to |
|---|---|---|
| (a) | Supplier name, address and GSTIN | All invoices |
| (b) | Consecutive serial number, max 16 characters, unique for the financial year | All invoices |
| (c) | Date of issue | All invoices |
| (d) | Recipient name, address and GSTIN/UIN | Registered recipients |
| (e) | Recipient name, address, delivery address, state name and code | Unregistered recipients, taxable value ₹50,000 or more |
| (f) | Same as (e) | Unregistered recipients below ₹50,000, if they ask |
| (g) | HSN code for goods or SAC for services | All, subject to digit notifications |
| (h) | Description of goods or services | All invoices |
| (i) | Quantity and unit or UQC | Goods |
| (j) | Total value of supply | All invoices |
| (k) | Taxable value after discount or abatement | All invoices |
| (l) | Rate of tax: CGST, SGST, IGST, UTGST, cess | All invoices |
| (m) | Amount of tax by head | All invoices |
| (n) | Place of supply with state name | Inter-state supplies |
| (o) | Delivery address, if different from place of supply | Where applicable |
| (p) | Whether tax is payable on reverse charge | All invoices |
| (q) | Signature or digital signature | Paper invoices; not needed for electronic invoices under the IT Act |
| (r) | QR code with IRN embedded | E-invoices under Rule 48(4) |
| (s) | Declaration that e-invoice is not required | Taxpayers above the e-invoice turnover who are not required to issue one |
Clauses (a) to (q) make the 17 core fields; (r) and (s) apply to the e-invoice regime.
Supplier and invoice identity fields: clauses (a) to (c)
(a) Supplier details. Use your legal name as per registration, your principal or additional place of business address, and the GSTIN of the registration making the supply. A business with registrations in two states must use the correct state's GSTIN on each invoice.
(b) Serial number. The number can contain letters, numerals, hyphen and slash, can run in one or multiple series, must not exceed 16 characters and must be unique for the financial year. See GST invoice number series rules for how to design a series.
(c) Date. The date of issue matters for time of supply and for the time limits in Rule 47 (30 days from supply for services; 45 days for banks, insurers and NBFCs).
Recipient fields: clauses (d), (e) and (f)
This is where the ₹50,000 threshold comes in.
- Registered buyer: name, address and GSTIN or UIN. Check the GSTIN before billing using the GSTIN validator; a single wrong digit sends your sale to someone else's credit ledger.
- Unregistered buyer, taxable value ₹50,000 or more: name, address, delivery address and the name of the state with its code are mandatory.
- Unregistered buyer, below ₹50,000: these details are needed only if the buyer asks for them.
There is a special proviso: for taxable services supplied through an e-commerce operator, OIDAR services, or online money gaming to an unregistered recipient, the invoice must carry the name of the recipient's state, regardless of value, and that is treated as the recipient's address on record.
Goods and value fields: clauses (g) to (k)
(g) HSN/SAC. The proviso to Rule 46 lets the Board notify how many digits a class of taxpayers must show. The current position by turnover is explained in HSN code digits on invoice.
(h) Description. Make it specific: "Cordless drill 18V with 2 batteries" is better than "Tools".
(i) Quantity and unit. For goods, show quantity with a unit or Unique Quantity Code such as NOS, KGS, LTR, MTR or BOX.
(j) Total value and (k) taxable value. Taxable value is after discounts shown on the invoice. Total value is taxable value plus taxes.
Tax fields: clauses (l) and (m)
Show the rate and the amount for each tax head separately. For an intra-state supply that is CGST and SGST (or UTGST), each at half the rate. For an inter-state supply it is IGST at the full rate. Cess is shown separately where it applies.
After the GST rate restructuring that took effect on 22 September 2025, most goods and services fall in the 5% or 18% slabs, with a 40% rate for specified sin and luxury goods. Make sure your item master reflects current rates; the GST calculator is handy for spot checks.
Supply fields: clauses (n), (o) and (p)
(n) Place of supply with state name is required for inter-state supplies. It is what justifies charging IGST rather than CGST+SGST.
(o) Delivery address is required when it differs from the place of supply, for example, a bill-to/ship-to sale.
(p) Reverse charge. State whether tax is payable on reverse charge. Print "Yes" or "No"; do not leave it blank. Reverse charge is covered in reverse charge mechanism.
Signature and e-invoice fields: clauses (q), (r) and (s)
(q) Signature. A paper invoice must be signed or digitally signed by the supplier or an authorised representative. A proviso removes this requirement for electronic invoices issued in accordance with the Information Technology Act, 2000.
(r) QR code. For notified e-invoice taxpayers (aggregate turnover above ₹5 crore in any year from 2017-18), the invoice must carry a QR code with the IRN embedded.
(s) Declaration. A taxpayer whose turnover is above the e-invoice threshold but who is not required to issue e-invoices must print the declaration set out in Rule 46(s).
What changes for exports and SEZ supplies?
The proviso to Rule 46 replaces clause (e) for exports. Instead, the invoice carries the recipient's name and address, the delivery address and the name of the country of destination. It must also carry the endorsement either "SUPPLY MEANT FOR EXPORT/SUPPLY TO SEZ UNIT OR SEZ DEVELOPER FOR AUTHORISED OPERATIONS ON PAYMENT OF INTEGRATED TAX" or the "UNDER BOND OR LETTER OF UNDERTAKING WITHOUT PAYMENT OF INTEGRATED TAX" version. Details in export invoice under LUT.
Worked example: auditing a real-looking invoice
A Kochi electrical contractor receives this invoice from a supplier in Coimbatore, Tamil Nadu:
- Supplier name and GSTIN: present
- Invoice number: "TN-CBE-WHOLESALE-2026-00451" (27 characters)
- Date: present
- Buyer GSTIN: present
- Items: 100 m copper cable at ₹85/m, HSN 8544, taxable value ₹8,500
- Tax shown: CGST 9% ₹765, SGST 9% ₹765
- Place of supply: not printed
- Reverse charge line: missing
- Total: ₹10,030
Audit result:
- Serial number fails clause (b): 27 characters is over the 16-character limit.
- Wrong tax head: Tamil Nadu to Kerala is inter-state. Tax should be IGST 18% = 8,500 × 0.18 = ₹1,530. The total (₹10,030) happens to be right, but the split is wrong.
- Place of supply missing (clause n), which is mandatory for an inter-state supply.
- Reverse charge line missing (clause p).
The fix is for the supplier to correct the tax head (typically by cancelling the original if it has not been reported, or through the correction route if it has) and issue a compliant invoice. The buyer should not book credit until the documents are right.
Rule 46 checklist: audit any invoice in two minutes
- Is "Tax Invoice" printed, with supplier name, address and GSTIN?
- Is the number 16 characters or fewer, and unique for this financial year?
- Is the date present?
- Is the buyer's GSTIN correct (or, for unregistered buyers at ₹50,000+, name, delivery address and state code)?
- Does every line have HSN/SAC, description, quantity with unit (goods), and taxable value?
- Are rate and amount shown for each tax head, and does the head match intra-state or inter-state?
- Is place of supply shown for inter-state supplies?
- Is the delivery address shown if it differs?
- Is the reverse charge status printed?
- Is the invoice signed, or issued electronically?
- If you are an e-invoice taxpayer, is the QR code with IRN printed?
Billing Software by Betterwork prints each of these fields from your item and customer masters, so the checklist is built into the template rather than left to memory.
How do the fields change for other document types?
Rule 46 is the template, but neighbouring rules reuse most of it, so learning it well pays off:
| Document | Rule | What differs from a tax invoice |
|---|---|---|
| Bill of supply | Rule 49 | No tax rate or tax amount; HSN, description and value stay |
| Revised invoice | Rule 53(1) | Words "Revised Invoice" and the original document's number and date |
| Credit or debit note | Rule 53(1A) | Nature of the document and the original invoice number(s) and date(s) |
| Delivery challan | Rule 55 | Issued in lieu of an invoice for job work, approval and similar movements |
All of them share the same numbering rule: a consecutive serial number of up to sixteen characters using letters, digits, hyphen and slash, unique for a financial year. Fix that once in your software and every document type benefits.
Common mistakes
- Leaving the buyer's address and state code off large B2C invoices of ₹50,000 or more.
- Using generic descriptions such as "material" or "services".
- No unit of measurement on goods lines.
- Blank reverse charge field.
- Printing only the total tax, not the rate and amount per head.
- Long branch prefixes that push the invoice number past 16 characters.
- Forgetting the QR code after crossing the e-invoice threshold.
Key takeaways
- Rule 46 has 17 core particulars, plus a QR code and a declaration for the e-invoice regime.
- The ₹50,000 threshold decides when unregistered buyers' details are mandatory.
- Exports swap the buyer-address clause for country of destination and a mandatory endorsement.
- Amount in words, bank details and logos are optional extras.
- Audit your template once against the checklist, then lock it.
This guide is general information, not tax advice. Rules last checked on 20 October 2026; confirm with your tax professional for your situation.