The first GST invoice I ever tried to create by hand took nearly 40 minutes — mostly spent googling "is my customer's state same as mine" and double-checking an HSN code I wasn't sure about. Once you know the sequence, it takes under five. Here's the actual process, not the textbook version.
Step 1 — gather what you need before you start
You'll move faster if you have these ready rather than hunting for them mid-invoice:
Your GSTIN and registered business address, exactly as it appears on your registration certificate.
The buyer's GSTIN (if they're GST-registered) and their billing address — the state on their GSTIN is what determines intra-state vs inter-state, not necessarily where the goods physically ship.
HSN codes for goods, or SAC codes for services, for every item you're billing. These aren't optional guesses — using the wrong code can misclassify the applicable GST rate.
Item list with quantities and your pre-tax (taxable) price per item.
Step 2 — figure out intra-state vs inter-state
Compare the state code on your GSTIN against the state code on the buyer's GSTIN (the first two digits of a GSTIN identify the state). Same state — you charge CGST + SGST, split equally. Different state — you charge IGST at the full rate, as a single line.
Example: your GST rate for an item is 18%. If the sale is intra-state, that's 9% CGST + 9% SGST. If it's inter-state, that's 18% IGST, shown as one figure. The total tax collected is identical either way — only how it's split (and which government it ultimately goes to) changes.
Step 3 — pick the right GST rate
Under the current GST 2.0 structure (effective since 22 September 2025), there are four slabs you'll realistically encounter:
0% — exempt goods and services: fresh produce, most healthcare, education services, and a few others.
5% — mass-consumption items: packaged food staples, many household goods, small-restaurant services.
18% — the standard rate most goods and services fall under: electronics, professional services, consulting, IT services, most B2B sales.
40% — sin and luxury goods only: tobacco, pan masala, aerated drinks, high-end luxury vehicles. Most small businesses will never bill at this rate.
If you're unsure which slab an item falls in, the HSN/SAC code is the actual determinant — not a guess based on what feels reasonable. This is exactly why having the correct code from Step 1 matters.
Step 4 — a worked example
Say you run a design consultancy in Karnataka, billing a client also registered in Karnataka, for ₹50,000 worth of services (SAC 998314, business consulting services, taxed at 18%).
| Field | Value |
|---|---|
| Taxable value | ₹50,000 |
| Transaction type | Intra-state (both parties in Karnataka) |
| CGST @ 9% | ₹4,500 |
| SGST @ 9% | ₹4,500 |
| Total invoice value | ₹59,000 |
If the same client were based in Maharashtra instead, you'd drop CGST/SGST and charge IGST @ 18% = ₹9,000 as a single line — same total of ₹59,000, different split.
Step 5 — finalize and number it
Assign the next sequential invoice number in your series, date it, double-check the buyer's GSTIN is correctly entered (a typo here is a common reason ITC claims get rejected on the buyer's end), and sign it.
Our GST Invoice Generator handles steps 2 through 5 automatically — it auto-splits CGST/SGST/IGST based on the states you enter, and has a built-in HSN/SAC autocomplete lookup so you're not guessing codes or rates by hand.