An invoice that gets queried is an invoice that gets paid late. In corporate transport the query is almost never about the amount — it is about a field that is missing, and the client’s system will not accept the document without it.
Here is the whole thing, field by field.
The header
| Field | Why it is there |
|---|---|
| The words Tax Invoice | Distinguishes it from a quotation or a delivery note |
| Your legal name and address | As registered, not your trading name |
| Your GSTIN | Without it the client cannot claim anything |
| Invoice number | Unique, sequential, from a defined series |
| Invoice date | The date of issue |
| Client’s legal name and address | As they are registered |
| Client’s GSTIN | This is what determines the tax split |
| Place of supply | The state, which decides CGST+SGST against IGST |
| Purchase order reference | Where the client uses one, this is what gets it paid |
| Period covered | For a consolidated monthly invoice, unambiguous dates |
Two of those are worth dwelling on. Place of supply is not the client’s head office — it is determined by the rules for the supply, and it decides whether you charge CGST plus SGST or IGST. And the PO reference is frequently the single reason an otherwise perfect invoice sits unpaid: the client’s system cannot match it to an approved order.
The lines
For a consolidated month, one line per trip or one line per group with a supporting statement:
| Column | Note |
|---|---|
| Date | Of the trip |
| Description | Route, or trip reference |
| Duty slip number | The evidence for this line |
| SAC | 996412 for passenger road transport |
| Quantity / distance | As recorded, not as estimated |
| Rate | From the agreed rate card |
| Taxable value | Before tax |
The duty slip number column is optional in the sense that no rule demands it, and essential in the sense that it turns a query into a four-minute lookup.
The tax block
| Line | Note |
|---|---|
| Total taxable value | Sum of the lines |
| CGST + SGST or IGST | Never both on one invoice |
| Reverse charge declaration | Where the recipient accounts for the tax |
| Round off | Shown, not absorbed |
| Total | In figures |
| Amount in words | Indian numbering — lakh and crore, not million |
| Signature or digital signature | With your authorised signatory |
Tax rules change and circumstances differ. This describes the fields an invoice carries and why a client checks them; confirm your own treatment with your accountant rather than relying on a web page.
The five omissions that get invoices returned
1. No PO reference. Their system rejects it before a human sees it.
2. Wrong tax split. CGST and SGST on an inter-state supply, or the reverse. It comes back, and the month slips by a week.
3. Missing SAC. The recipient needs it for their own filing.
4. Mixed treatments on one document. Some trips forward charge, some reverse charge, one invoice. That is two invoices, each internally consistent.
5. No supporting slips. Not a rule, but the practical difference between a query answered in minutes and a query answered in days.
Numbering, which is where the arguments start
Three things about the series:
- Run it on the April–March financial year and make the year visible —
INV/26-27/0093says more thanINV/93. - The counter only goes forwards. If a number was issued, it was issued.
- A cancelled invoice does not leave a hole. A tax series with a gap in it is a question you will be asked to answer, so a withdrawn invoice stays visible as cancelled rather than disappearing.
Why this is worth systematising
Fourteen header fields, seven columns, seven tax lines. Once a month, across every corporate account, assembled by whoever is free that week.
It is not that anyone is careless. It is that the task has more places to go slightly wrong than a person can hold, and each one costs a week of payment terms.
Our corporate billing and GST invoicing page covers a month of trips becoming one invoice with the tax handled, and the duty slip post covers the document that sits behind each line.