A GST invoice missing even one mandatory field can be rejected during an audit, or worse, block your buyer from claiming input tax credit. Yet most small traders and shop owners in Pollachi still build invoices in Word or Excel from a template someone shared on WhatsApp two years ago, with fields that stopped being compliant after the last GST amendment.
Our GST invoice generator handles the compliance checklist automatically. Here's what it covers and why each field exists.
What Makes an Invoice "GST Compliant"
Under Rule 46 of the CGST Rules, a tax invoice must include specific fields, or it isn't a valid tax invoice at all, regardless of how good it looks. Missing any of these can invalidate the input tax credit your customer would otherwise claim:
- Invoice number and date, sequential and unique for the financial year
- Supplier's name, address, and GSTIN
- Recipient's name, address, and GSTIN (if registered)
- HSN or SAC code for each item or service
- Description, quantity, and unit of each item
- Taxable value before tax
- Applicable GST rate and amount, split correctly into CGST, SGST, or IGST
- Place of supply, especially for inter-state transactions
- Signature of the supplier or an authorised representative
Miss the HSN code and your invoice is technically non-compliant even if every number on it is correct. This is the single most common mistake we see in manually created invoices.
CGST + SGST vs IGST: Getting the Split Right
If you're selling within Tamil Nadu, the tax splits equally into CGST and SGST. Sell to a customer in Kerala or Karnataka, and the entire tax amount goes under IGST instead. Mixing these up is a common error that shows up during return filing and creates a mismatch between your GSTR-1 and the buyer's GSTR-2B.
Example: a ₹10,000 sale within Tamil Nadu at 18% GST becomes ₹900 CGST plus ₹900 SGST, total tax ₹1,800. The same sale to a Bangalore-based buyer becomes ₹1,800 IGST, no CGST or SGST at all. Our invoice generator detects the buyer's state from the GSTIN and applies the correct split automatically, so you don't have to remember the rule for every invoice.
Finding the Right HSN Code
HSN (Harmonized System of Nomenclature) codes classify goods; SAC codes classify services. Getting the wrong code on an invoice can trigger a mismatch with your GSTR-1 filing and, at higher turnover, attract scrutiny. Businesses with turnover above ₹5 crore must use a 6-digit HSN code; below that threshold, a 4-digit code is usually enough.
Not sure of your code? Use our HSN code finder before creating the invoice; it searches by product description and returns the matching code along with the applicable GST rate.
Step-by-Step: Generating Your Invoice
Open the GST invoice generator and fill in your business details once; the tool remembers them for the next invoice. Add the buyer's GSTIN and address, then add line items with description, HSN code, quantity, and rate. The tool calculates CGST/SGST or IGST automatically based on both GSTINs, generates the invoice number in sequence, and produces a PDF you can download or send directly.
No login is required and no data is stored on our servers beyond the current session, which matters if you're generating invoices for a client's business rather than your own.
Common Mistakes We See in Manually Created Invoices
Duplicate invoice numbers across financial years. Missing place-of-supply for inter-state sales. Rounding tax to the nearest rupee instead of calculating it precisely (small, but it fails a strict audit). Forgetting to mention "Reverse Charge Applicable" when it genuinely applies. And the most frequent one: applying the wrong GST rate because the shop owner is going from memory instead of checking the current rate for that HSN code.
Do You Need to Register for GST Before Using This Tool?
No. The invoice generator works whether or not you're GST-registered. If you're below the registration threshold (₹40 lakh for goods, ₹20 lakh for services in most states, lower limits in special category states), you simply skip the GSTIN field and issue a regular bill of supply instead of a tax invoice. Not sure if you're required to register? Check with our GST registration checker first.
Frequently Asked Questions
Is a handwritten GST invoice valid?
Yes, as long as it contains every mandatory field under Rule 46. The format doesn't have to be digital or printed; the content is what makes it valid. In practice, though, handwritten invoices are far more likely to miss a required field or contain a calculation error.
What happens if I send an invoice without a GSTIN to a registered buyer?
Your buyer won't be able to claim input tax credit on that purchase, since ITC claims require your GSTIN to appear on the invoice. If you're registered but simply forgot to add it, correct and reissue the invoice before your buyer files their return.
Can I edit an invoice after generating it?
You can regenerate a corrected invoice, but under GST rules you generally cannot silently edit and reissue the same invoice number once it's been shared with the buyer or reported in your GSTR-1. Significant corrections need a credit note or debit note against the original invoice number instead.
Do I need a digital signature on a GST invoice?
Not for a standard invoice; a physical signature or a digitally rendered signature image is sufficient for most businesses. E-invoicing (mandatory only above certain turnover thresholds) has its own separate requirements involving IRN generation and a QR code, which is a different system from a standard tax invoice.
