Past Due Invoice: 5 Follow-Up Steps Before You Lose the Money

Do not wait a week. Do not wait for the client to "get around to it." The day the invoice crosses its due date, send a written reminder.

Send a written reminder promptly when you do not receive payment by the due date, resending the invoice with a message that you have not received payment. You can mark the invoice as "past due" or use a message such as "Did you forget? Your payment is due."

Keep the tone friendly. Most late payments are not malicious. Late-paying customers generally fall into three categories: those who want to pay but have real financial problems, those who prefer to delay or juggle payments, and those who will do whatever possible to avoid paying. For the first two categories, a simple reminder is often enough to move the invoice to the top of their stack.

This reminder should go out by email and by text. A text is harder to ignore than an email buried under 40 others. If you use Nudge, your reminders go out automatically on the schedule you set, so no past due invoice slips through because you were busy on a job site.

If the written reminders have not worked after two weeks, call the client directly.

The recommended approach: start with automated email reminders before the due date, followed by a direct phone call 15 days past due. A phone call does two things a text cannot. It lets you hear whether the client is avoiding you or genuinely struggling, and it creates a personal commitment that is harder to break than ignoring a notification.

During the call, confirm they received the invoice, ask if there is a dispute about the work or the amount, and get a specific date they commit to paying. Write that date down. If they say "end of the month," you now have a concrete deadline to reference in your next follow-up.

This is also the moment to explore a payment plan if cash flow is the issue. Sometimes a client who cannot pay $5,000 today can pay $2,500 this week and $2,500 next month.

By 30 days past due, the invoice has moved from "forgot about it" to "deprioritised." This is when late fees earn their place.

Late fees on overdue invoices typically range from 1.5% to 3% per month. The important detail: these fees need to be stated in your original contract or service agreement before you can apply them. You cannot retroactively invent a penalty.

If your contracts already include this language, send a revised invoice with the accrued late fee clearly itemised. If your contracts do not currently include late fee language, add it before your next job. For existing past due invoices without that clause, you still have leverage in the steps that follow, but you lose this particular tool.

Along with the late fee, send another written reminder. This one should be firmer than the first. State the original due date, the number of days overdue, and the total now owed including any late fee.

If an invoice hits 60 days past due, send a formal letter via certified mail. This serves as a final warning and is often required evidence if you later go to court.

A demand letter is different from a reminder. It is a formal document that creates a legal record. It should include the total amount owed, your contact information, where the client should send payment, and a deadline for payment. Depending on what state you are filing in, you may be required to demand payment from your client before filing a small claims court lawsuit.

You do not need an attorney to write a demand letter, though if the amount at stake justifies the cost, an attorney-signed letter may carry more weight.

Send the demand letter via certified mail so you have proof of delivery. Keep a copy. If you end up in court, this letter is one of the most important pieces of documentation you will have.

If 90 days have passed and you have sent reminders, made phone calls, applied late fees, and mailed a formal demand letter with no result, you have two options left.

Whichever step you are on, document everything. Keep a chronological log of all invoices, payment history, and communication attempts, including dates, times, and summaries of calls.

If you reach Step 5, this record is what separates a strong case from a weak one. Judges and collections agencies both need evidence that you made reasonable efforts to collect before escalating.

Nudge keeps a record of every reminder sent and every response received, so your documentation builds itself as the escalation progresses. For more on how automated reminders work, see the Nudge FAQ.

The QuickBooks Late Payments Report found that small businesses with a higher volume of overdue invoices were 1.4 times more likely to report cash flow problems (50%) compared to those with fewer late payments (34%).

A single past due invoice might feel manageable. But stack a few of them up, and you are suddenly borrowing against credit cards to make payroll, delaying materials purchases, or turning down new work because you cannot afford to front the costs.

Following these five steps in order, on a predictable schedule, is not about being aggressive. It is about treating your invoicing like what it is: the financial infrastructure of your business. The sooner you follow up, the more likely you are to get paid. And the less likely you are to end up in a courtroom trying to recover money you earned months ago.