1. No payment terms on the invoice
If your invoice doesn't say when payment is due, your client decides that for themselves, and they'll usually decide in their own favour. State the terms plainly: "Payment due within 14 days of invoice date." It also helps if you ever need to collect, since the terms are on the record. Our step-by-step invoice guide covers where they go.
2. Missing banking details
This one is more common than it should be. A client wants to pay, can't find your account number, sets the invoice aside, and it never comes back up. Put your bank name, account number, branch code, and payment reference on every invoice, every single time.
3. Tax invoices that don't meet SARS requirements
If you're VAT-registered and your invoice is missing a required field (your VAT number, the serial number, the VAT amount, any of it), a client's accountant can reject their VAT claim. That turns into a dispute that delays payment and strains a relationship you were probably trying to build. The tax invoice checklist has every field.
4. Inconsistent invoice numbering
SARS requires an individual serial number on every tax invoice, and a running sequence is the easiest way to show none are missing. Dates ("INV-2026-05-14") or random strings make that hard to prove. Use a simple format instead, something like INV-2026-0001, INV-2026-0002, and so on, and never skip or reuse a number. Invo numbers your invoices automatically.
5. No late payment clause
If you haven't agreed a late payment policy, you're left relying on the law's default interest rate, and generally only from when you formally demand payment. Agreeing it up front gives you a clearer basis. Add a simple clause to your quote and invoice, for example: "Invoices not settled within 30 days of the due date will accrue interest at 1.5% per month." Interest can't run past the amount owed, and consumer sales have extra rules, so get advice for larger amounts.
6. Waiting too long to follow up
The most common invoicing mistake of all is sending the invoice, then going quiet. Set a reminder to follow up the day after the due date, every time. Invo shows overdue invoices and has reminders ready to send (see the features page), and 8 ways to get paid faster has more habits that help.
