Most GST problems don’t happen because businesses hide income or skip tax. They happen because of small invoice mistakes—missing GSTIN, wrong place of supply, no HSN code, or incomplete tax breakup.
That’s exactly why Rule 46 of the CGST Rules exists. It clearly lists what every GST tax invoice must contain. Miss even one mandatory field, and your invoice may become non-compliant. That can lead to ITC denial for your customer and notices for you.
Let’s go through each mandatory field slowly and practically—no legal jargon, just real understanding.
What Is Rule 46 of CGST Rules?
Rule 46 specifies the mandatory particulars that must appear on a GST tax invoice issued by a registered supplier.
It applies to:
- Goods
- Services
- B2B supplies
- B2C supplies (with some relaxations)
If these details are missing or incorrect, the invoice may not be accepted during audits or return matching.
Mandatory Fields of a GST Tax Invoice (Explained Simply)
Below are the core fields you must include.
1. Supplier Details
Every GST invoice must clearly mention:
- Supplier’s name
- Address
- GSTIN
This identifies who is collecting GST. Wrong GSTIN = ITC blocked for buyer.
2. Invoice Number (Unique & Consecutive)
- Must be unique for each financial year
- Can contain alphabets, numbers, or special characters
- Maximum 16 characters
No two invoices in the same year can have the same number.
3. Date of Issue
Invoice date decides:
- Time of supply
- Tax period
- Interest liability
Even one-day delay can create compliance issues.
4. Recipient Details (If Registered)
If the buyer is registered:
- Name
- Address
- GSTIN
For unregistered buyers:
- Name and address (if invoice value > ₹50,000)
This helps GST match ITC claims.
5. HSN or SAC Code
- HSN → Goods
- SAC → Services
Rules:
- Turnover ≤ ₹5 crore → 4 digits
- Turnover > ₹5 crore → 6 digits
Wrong code = wrong tax rate = future notice.
6. Description of Goods or Services
This must clearly describe:
- Nature of goods/services
- Type
- Category
Vague descriptions like “items” or “services” often create audit problems.
7. Quantity & Unit (For Goods)
For goods invoices:
- Quantity
- Unit (kg, pcs, liters, etc.)
This links invoice to actual movement of goods.
8. Value of Supply
Invoice must show:
- Total value
- Taxable value (after discounts)
Discounts must be clearly mentioned and linked to agreements if applicable.
9. Tax Rate & Tax Amount
Invoice must separately show:
- CGST
- SGST
- IGST
Along with:
- Applicable rate
- Amount charged
Lump-sum tax values are not acceptable.
10. Place of Supply (Inter-State Supplies)
Mandatory for:
- Inter-State transactions
- Export supplies
Place of supply decides whether CGST+SGST or IGST applies.
Wrong place of supply is one of the top GST litigation issues.
Reverse Charge Indicator
If reverse charge applies:
- Invoice must clearly mention “Tax payable under reverse charge”
Missing this can shift tax liability incorrectly.
Signature or Digital Signature
Invoice must be:
- Physically signed or
- Digitally signed
For e-invoices, IRP signature is auto-generated.
Additional Fields Required in Some Cases
Depending on transaction type, invoice may also include:
- E-invoice IRN & QR code
- Export endorsement
- LUT/Bond reference
- Payment terms
Not mandatory for all, but critical when applicable.
Common Invoice Mistakes Businesses Make
- Missing place of supply
- Wrong GSTIN of buyer
- Incorrect HSN/SAC
- No tax breakup
- Duplicate invoice numbers
- No reverse charge mention
These mistakes usually surface during:
- GST audits
- ITC mismatches
- Department scrutiny
Why Rule 46 Matters More Than You Think
GST runs on invoice matching.
Your invoice:
- Feeds into GSTR-1
- Appears in buyer’s GSTR-2B
- Decides ITC eligibility
One missing field can:
- Block buyer’s ITC
- Damage business relationship
- Trigger notices
Rule 46 keeps the entire chain clean.
Simple GST Invoice Checklist (Practical Tip)
Before issuing any invoice, quickly check:
- GSTINs correct
- Invoice number unique
- Date correct
- HSN/SAC added
- Tax breakup clear
- Place of supply mentioned
- Signature present
This 30-second check saves months of trouble.
To better understand how GST invoicing works in real situations, you may also find these related guides useful:
- If you’re just starting with GST documentation, read our beginner-friendly guide on Understanding GST Tax Invoices: A Simple Beginner Guide to know why invoices are the backbone of GST compliance.
- Businesses dealing in physical products should also go through GST Tax Invoice Rules for Goods: Time, Format & Cases to understand when and how invoices must be issued for goods.
- Service providers can avoid common compliance mistakes by reading GST Tax Invoice Rules for Services: Time, Limits & Use, especially for advance payments and continuous supply.
- If your business operates on long-term contracts or subscriptions, Continuous Supply Under GST: Goods vs Services Explained will help you issue invoices at the correct time.
- For traders sending goods on approval or for exhibitions, GST Invoice Rules for Sale or Return & Exhibition Goods explains special cases where invoices are not issued immediately.
These articles together give you a complete and practical understanding of GST invoicing, from basics to advanced scenarios.
FAQs
1. Is Rule 46 applicable to all GST invoices?
Yes, unless specific relaxation is provided by GST rules.
2. Can invoice format be customised?
Yes. Design is flexible, but mandatory fields are compulsory.
3. Is HSN mandatory for all invoices?
Yes, based on turnover limits.
4. Is signature mandatory on GST invoice?
Yes—physical or digital.
5. What happens if mandatory fields are missing?
Invoice may be treated as invalid, and ITC can be denied.
6. Are e-invoices different from normal invoices?
Fields are similar, but e-invoices require IRN and QR code.
