The 6 Most Common Invoicing Mistakes SA Businesses Make

Most invoice problems are small. A missing field, a vague due date, a number that doesn't follow the last one. None of them looks serious when you hit send, but each gives a client a reason to wait, query the invoice or send it back. These are the six we see most, what each one costs you, and how to fix it.

1. No payment terms on the invoice

If your invoice doesn't say when payment is due, your client decides for themselves, and they'll usually decide in their own favour. "Payment due within 14 days of invoice date" is the minimum. A calendar date is better still. "Due 14 November 2026" can't be misread, whereas "30 days" invites an argument over whether the clock started on the invoice date, the delivery date or the day it landed in the client's inbox.

Put the same terms on your quote. A client who agreed to them before the work started has a much harder time claiming they never saw them on the invoice. Our step-by-step invoice guide shows where terms sit on the page.

2. Missing banking details

A client is ready to pay, can't find your account number, sets the invoice aside, and it never comes back up. Every invoice should carry the bank name, the account holder's name, the account number, the branch code and the account type. Add a payment reference too, and make it the invoice number. A R12,000 deposit with no reference is a line on your bank statement that you have to chase.

If you change banks, check that your saved invoice template changed with you. Old account numbers living on in a template are an easy way to send a client's money somewhere it won't arrive.

3. Tax invoices that don't meet SARS requirements

If you're VAT registered, a full tax invoice has to show certain details. SARS lists them: the words "Tax Invoice", "VAT Invoice" or "Invoice"; your name, address and VAT number; the client's name and address, plus their VAT number if they're a VAT vendor; a serial number and the date; a description of the goods or services; the quantity or volume; and the value of the supply, the VAT charged and the total. A description like "services" or "work done" is too thin to count.

The R5,000 line matters. A full tax invoice is required when the supply is worth more than R5,000. At R5,000 or less you may issue a shorter abridged invoice, and at R50 or less no tax invoice is required at all. The VAT Act also expects you to issue the invoice within 21 days of the supply.

The cost of getting it wrong lands on your client. A VAT-registered client needs a valid tax invoice to claim the VAT back, and SARS can disallow a claim that rests on an invoice with a missing field. Their accountant sends it back to you, the payment waits, and the conversation you wanted to have about the next job becomes a conversation about paperwork. The tax invoice checklist goes through every field.

The reverse mistake is just as common. If you aren't VAT registered, you shouldn't show a VAT number or charge VAT, and invoicing without VAT has its own short checklist.

4. Inconsistent invoice numbering

Every tax invoice needs its own serial number, and an unbroken sequence is the easiest way to show that none are missing. A date such as "INV-2026-10-14" or a random string makes that hard to prove, and two invoices issued on the same day get the same number. Use a plain running format like INV-2026-0001, INV-2026-0002 and so on.

Never reuse a number, and don't delete an invoice to fix a mistake. If one went out wrong, cancel it with a credit note and issue a new invoice with the next number, so the record shows what happened. Invo numbers your invoices automatically, which is most of the point of using it.

5. No late payment clause

If you haven't agreed a late payment policy, you're left with the law's default. That default is the prescribed rate of interest under the Prescribed Rate of Interest Act, which was 10.25% a year from 1 March 2026 and moves with the repo rate. When interest starts to run can also be argued over, and a formal letter of demand usually comes into it. Agreeing a clause up front removes that argument.

A simple clause on the quote and the invoice is enough: "Invoices not settled within 30 days of the due date will accrue interest at 1.5% per month." Keep the rate sensible. The National Credit Act caps interest on overdue accounts at 2% per month, and a clause above that cap is unlikely to hold. Consumer sales carry extra rules, so get advice before you rely on a clause for a large amount.

6. Waiting too long to follow up

The most common invoicing mistake is sending the invoice and then going quiet. Late payment often doesn't mean a client refuses to pay. The invoice may simply have sat below a pile of other emails.

Set a reminder for the day after the due date, every time, and send a short, friendly message with the invoice attached. Chasing early costs you nothing and keeps the tone light. Leaving it for two months turns the same message into a confrontation, and by then the client may no longer remember the details of the job. A debt generally prescribes three years after it falls due, which is longer than most people leave it, but the evidence and the goodwill fade much sooner. Invo shows overdue invoices and has reminders ready to send (see the features page), and our guide to following up an unpaid invoice gives wording for each stage. 8 ways to get paid faster covers the habits that mean you chase less.

A two-minute check before you send

Before any invoice goes out, read it as the client's accountant would. Is there a due date? Can they see where to pay and what reference to use? Does it have a unique number and a date? If you're VAT registered, is the VAT number there and the VAT shown on its own line? Do you have the late payment terms on it? Two minutes at this stage saves the week it takes to fix a problem afterwards.