Almost everyone who invoices clients directly ends up chasing a late payment eventually. It is uncomfortable, but there is a straightforward, professional way to handle it that rarely damages a relationship worth keeping.
Start before it is even late
A short, friendly reminder a day or two before the due date - "just a heads up your invoice is due Friday" - catches genuine oversights before they become genuine problems, and does not read as an accusation because nothing is overdue yet.
The first chase: assume good faith
If the due date passes, the first message should assume the simplest explanation: it was missed, not ignored. "Hi [name], just checking you received invoice #104 - it looks like it's a few days overdue, let me know if there's an issue on your end." This gives them an easy way to respond without feeling called out.
The second chase: be specific and direct
If a week or more passes with no response, the tone can firm up without becoming hostile. State the invoice number, amount, and how overdue it is, and ask for a specific date they can pay by. Vague chasing gets vague responses - a specific question gets a specific answer.
When to stop being patient
No response at all after two clear attempts, roughly a week apart
Repeated promises to pay "by Friday" that keep moving
The client becomes unreachable through their usual channel
At that point it is reasonable to mention late payment interest (UK small businesses are entitled to statutory interest and compensation under the Late Payment of Commercial Debts Act for business-to-business invoices), and, for larger amounts, to consider a formal letter before action as the next step.
Make chasing easier on yourself
A dashboard that shows exactly what is overdue and by how long removes the guesswork of "have I already chased this one?" - Invoito flags overdue invoices automatically so you are never chasing from memory.