What is the time limit to issue a GST invoice?

For goods, the invoice must be issued before or at the time of supply. For services, within 30 days of the date of supply (45 days for banks and NBFCs).

Is a GST invoice mandatory for all transactions?

Yes, for all registered taxpayers making taxable supplies. For B2C transactions below ₹200 you may issue a consolidated invoice, but B2B transactions always require a full tax invoice.

Can I create a GST invoice without software?

Yes, you can create one manually on paper or in Excel as long as all mandatory fields under GST Rule 46 are present. Software makes it faster and reduces errors.

What happens if I issue an incorrect GST invoice?

You must issue a credit note or debit note to correct it. You cannot simply cancel and re-issue with the same number.

Is a digital signature required on a GST invoice?

Not mandatory. A handwritten or printed name of the authorized signatory is sufficient. E-invoices use a digital signature from the IRP automatically.

What is the difference between a tax invoice and a bill of supply?

A tax invoice is issued for taxable supplies by regular taxpayers. A bill of supply is issued for exempt supplies or by composition taxpayers who cannot charge GST.

Home / Guides / How to Create a GST Invoice in India

How to Create a GST Invoice in India

A compliant GST invoice needs specific fields, correct tax splits, and a valid HSN code. Here is exactly what to include and how to generate one fast.

Updated 2026-09-24 · A reference guide from Ledgester

Key facts

Governed by GST Rule 46 (CGST Rules, 2017)
Must be issued within 30 days of supply (45 days for banks/NBFCs)
Sequential invoice numbering is mandatory
HSN code required for goods; SAC code for services
CGST + SGST for intra-state; IGST for inter-state supply

What fields are mandatory on a GST invoice?

GST Rule 46 of the CGST Rules, 2017 specifies every field a tax invoice must carry. Missing even one can lead to ITC denial for your buyer or a scrutiny notice.

Legal name and GSTIN of the supplier
Legal name, address, and GSTIN of the recipient (for B2B invoices)
Consecutive invoice number and date (the number must be unique per financial year)
HSN/SAC code — mandatory above ₹5 lakh aggregate turnover
Description of goods or services, quantity, unit, and unit value
Taxable value after any discount
CGST rate and amount, SGST rate and amount (for intra-state supply)
IGST rate and amount (for inter-state supply)
Place of supply (state name and state code)
Whether the tax is payable on reverse charge
Signature or digital signature of the authorized signatory

For e-invoices (mandatory above ₹5 crore turnover), the Invoice Reference Number (IRN) and QR code generated by the IRP must also appear on the invoice.

How do you calculate CGST and SGST on an invoice?

The split between CGST and SGST depends on whether the supply is intra-state or inter-state. The place of supply determines which tax applies.

Intra-state supply (supplier and buyer in same state): split the applicable GST rate equally between CGST and SGST. For example, 18% GST becomes 9% CGST + 9% SGST.
Inter-state supply (supplier and buyer in different states, or supply to a Union Territory): apply the full GST rate as IGST. For example, 18% GST becomes 18% IGST.
Exports: zero-rated. IGST at 0% or supply made under a Letter of Undertaking (LUT) with no tax.

Taxable Value × Rate ÷ 100 = Tax Amount
Example: ₹10,000 × 18 ÷ 100 = ₹1,800 total GST
Intra-state: CGST = ₹900 + SGST = ₹900
Inter-state: IGST = ₹1,800

Always apply the tax rate to the taxable value, not the gross value. Subtract any trade discount before calculating tax.

When must a GST invoice be issued?

The time limit for issuing a GST invoice is set by Section 31 of the CGST Act and differs for goods and services.

Goods (non-continuous supply): before or at the time of removal or delivery, whichever is earlier
Continuous supply of goods: before or at each statement of account or on/before each payment due date
Services (general): within 30 days from the date of supply of service
Banking, NBFCs, insurance companies: within 45 days from the date of supply
RCM supplies from unregistered persons: invoice must be raised by the recipient within 30 days of receipt of supply

Issuing an invoice beyond the prescribed time limit is an offence under Section 122 and can attract a penalty of ₹10,000 or the amount of tax evaded, whichever is higher.

What is the correct HSN code format for GST invoices?

HSN (Harmonised System of Nomenclature) codes must appear on every invoice for goods above certain turnover thresholds. Services use SAC (Services Accounting Code) instead.

Turnover below ₹1.5 crore: HSN code is optional (though recommended)
Turnover between ₹1.5 crore and ₹5 crore: 4-digit HSN code is mandatory
Turnover ₹5 crore and above: 6-digit HSN code is mandatory
Services: always use the applicable SAC code regardless of turnover

An incorrect or missing HSN/SAC code can trigger a scrutiny notice from the GST officer and may affect your buyer's ability to reconcile ITC. When in doubt, search the official HSN finder on the GSTN portal or within Ledgester.

How to create a GST invoice step by step

The entire process takes under two minutes in modern invoicing software. Here is how it works in Ledgester:

Open your invoicing software or Ledgester. Navigate to the invoice creation screen from the dashboard.
Enter buyer's GSTIN and legal name. For B2B invoices, type the buyer's GSTIN and the system auto-fills their legal name and state, which sets the place of supply automatically.
Add line items with HSN/SAC code, quantity, and rate. For each product or service, enter the description, HSN or SAC code, quantity, and unit rate. The system calculates the taxable value.
System auto-calculates CGST/SGST or IGST. Based on the place of supply, the software applies CGST+SGST (intra-state) or IGST (inter-state) at the correct rate. Verify the tax split before proceeding.
Add payment terms and UPI QR code (optional). Set a due date and add a UPI QR code to make it easy for buyers to pay immediately.
Preview, download PDF, and share. Review the invoice, download as PDF, and share directly on WhatsApp or email. Keep a copy in your records for reconciliation.

What are the common GST invoice mistakes to avoid?

Small errors on an invoice can have significant downstream consequences — from ITC denial for your buyer to penalty notices for you.

Wrong GSTIN on the invoice: if the buyer's GSTIN is entered incorrectly, they cannot claim ITC. Always verify from the GSTN portal before saving.
Missing or incorrect HSN/SAC code: triggers scrutiny and can cause your GSTR-1 to be flagged during auto-validation.
Wrong place of supply: applying CGST+SGST when IGST is required (or vice versa) creates a tax mismatch that neither party can easily correct.
Non-sequential invoice numbers: gaps in invoice numbering are a red flag during audits. Never reuse or skip numbers.
Issuing an invoice beyond the time limit: for services, issuing after 30 days (or 45 days for banks) is an offence and attracts penalty.
Issuing a revised invoice instead of a credit/debit note: once an invoice is issued, corrections must be made via credit notes or debit notes, not by cancelling and reissuing with the same number.

Frequently asked questions

What is the time limit to issue a GST invoice?: For goods, the invoice must be issued before or at the time of supply. For services, within 30 days of the date of supply (45 days for banks and NBFCs).
Is a GST invoice mandatory for all transactions?: Yes, for all registered taxpayers making taxable supplies. For B2C transactions below ₹200 you may issue a consolidated invoice, but B2B transactions always require a full tax invoice.
Can I create a GST invoice without software?: Yes, you can create one manually on paper or in Excel as long as all mandatory fields under GST Rule 46 are present. Software makes it faster and reduces errors.
What happens if I issue an incorrect GST invoice?: You must issue a credit note or debit note to correct it. You cannot simply cancel and re-issue with the same number.
Is a digital signature required on a GST invoice?: Not mandatory. A handwritten or printed name of the authorized signatory is sufficient. E-invoices use a digital signature from the IRP automatically.
What is the difference between a tax invoice and a bill of supply?: A tax invoice is issued for taxable supplies by regular taxpayers. A bill of supply is issued for exempt supplies or by composition taxpayers who cannot charge GST.

Try the GST invoice generator → Open Ledgester →

This guide is general information, not professional tax advice, and GST rules change through CBIC notifications. Verify the current position for your situation or consult a qualified professional before acting.