An invoice that gets paid late is often an invoice that was missing something a finance team needed. Requirements vary by country, but the underlying logic does not: an invoice has to identify the parties, describe the work, state the tax treatment, and say how and when to pay.
The fields that matter everywhere
- A unique invoice number. Sequential and never reused — this is what accounting systems key on, and duplicates cause genuine reconciliation problems.
- Issue date, and separately the supply or service date if they differ.
- Your business name, address, and tax registration number where you have one.
- The client's legal entity name and address — the registered entity, not a trading name or a contact's personal name.
- Itemised lines with description, quantity, unit price, and line total.
- Subtotal, tax, and the final amount due, each shown separately.
- Payment terms and bank details.
The invoice number deserves emphasis because it is the one people improvise. Restarting numbering each year is fine if the sequence is unambiguous; reusing a number because a previous invoice was cancelled is not, and creates an audit problem.
Being specific in descriptions
"Consulting services — 8,000" is a line that invites a query, and queries are what delay payment. "Website redesign: 4 page templates and responsive testing, as per proposal dated 3 March" gives an approver enough to authorise without going back to anyone. If a purchase order exists, put the PO number on the invoice — many finance systems will not process an invoice without it.
Indian GST specifics
For GST-registered businesses in India the requirements are stricter, and getting them wrong affects whether your client can claim input credit.
- Both parties' GSTIN, where the client is registered.
- HSN codes for goods, or SAC codes for services.
- Place of supply, which determines the tax split.
- CGST and SGST shown separately for supply within a state; IGST for supply between states.
That last distinction is the common error. Intra-state supply splits the tax into central and state components; inter-state supply uses a single integrated tax. Getting it wrong means your client cannot claim credit properly, and they will send the invoice back.
Terms that actually affect payment timing
"Net 30" is standard but ambiguous about the start date — 30 days from invoice date and 30 days from receipt can differ by a week. State it explicitly. If you charge interest on late payment, it must be on the invoice from the outset to be enforceable in most jurisdictions; adding it afterwards does not work.
Send the invoice to the finance address rather than your day-to-day contact where one exists. A significant share of late payments are invoices sitting in an individual's inbox rather than in the payment run.
Keep copies
Most jurisdictions require invoices to be retained for several years — commonly six in the UK, and similar elsewhere. Since a browser-based generator does not store anything for you, download and file each invoice as you issue it.