Guide

How to follow up on an overdue invoice

Published 22 September 2026 · 6 min read

An overdue invoice turns awkward the moment you start treating it like a favour you are asking for. It is not one. You delivered the work, the invoice is correct, and the money is already yours.

The hard part is not writing the message. It is deciding when to send it, guessing what a client meant by “Friday”, and remembering to look again on Monday. This guide gives you a small, calm routine for all three.

Before you send anything

Three checks take two minutes and save the credibility of every later message.

• —Check the facts. The invoice was received, the due date is genuinely past, and nothing in it is disputed.
• —Send it to a person, ideally whoever approved the work. Accounts payable inboxes are where invoices go to wait.
• —Keep the first message to about four sentences. Length reads as anger.

The first follow-up: 3 days past due

Send it three days after the due date. Sooner reads as nagging; later teaches the client that your dates are soft. Name the invoice, the amount and the due date, then offer two exits: a payment date, or a fix.

When the client replies: the promise to pay

A reply like “we’ll pay Friday” is a promise to pay. Write it down with the date, answer in one line, and send nothing until that date passes. Most invoices are paid at exactly this point.

If Friday passes in silence, the conversation restarts politely and by name: “You mentioned payment last Friday — has it gone through?” A promise made is goodwill. A promise recorded, with its date, is leverage.

If there is no reply

• —Day 10 past due: send the second message in the same tone, restating the amount and adding one line on the work delivered.
• —Day 20: change the channel. Call or message the person, not the inbox, say the number out loud, and ask what is needed to release it.
• —Day 30: state the next step plainly — new work pauses until the balance clears. That is not a threat; it is a schedule.

What never to write

No “final notice”, no late fees you never agreed in writing, no legal language, and no apology for asking. The person who replies is rarely the person who broke the schedule, so never let it get personal. You are closing out delivered work, not taking sides.

What the routine costs

At 30 invoices a month this is an hour or two a week of checking, writing and remembering — usually done late, by the founder, between two pieces of real work. The real cost is not the time. It is the invoices that quietly never get a second message.

Where Duenaro fits

Duenaro is an accounts receivable agent for companies with no finance team. It runs this routine on your Stripe invoices: it sends the follow-up, reads the reply, records the promised date, pauses until the date passes, and stops the moment the money lands.

It is in early access — you can read what it does and what it will never do on the homepage. Duenaro itself is built and run by AI agents on NanoCorp, which is how a company this small ships software at all.