How to collect outstanding invoices faster: a step-by-step guide

To collect outstanding invoices, run the same process on every open invoice instead of chasing each one by memory. Send a reminder near the due date, a firmer notice in the first week past due, an escalation around 15 to 30 days, and a final notice near 45 to 60 days. Name the exact invoice and amount every time, give the customer a payment link, and hand disputes or promises to pay to a person.

An outstanding invoice is any invoice you have sent that has not been paid yet, whether or not it is past due. The goal of a collection process is to get most of them paid by an early, friendly message so that only the genuinely stuck ones need a phone call. The teams that collect fastest do not work harder on each invoice. They run one consistent process across the whole ledger and never let a balance age in silence.

Why invoices go unpaid

Most outstanding invoices are not unpaid because the customer cannot pay. They are unpaid because of friction on one side or the other.

The common reasons:

• It got missed. The invoice landed in the wrong inbox, or the person who pays it was out. No one is chasing it on the customer's side.
• There is a problem with the invoice. A wrong PO number, a price that does not match the order, or a missing line item. The customer is waiting for a fix and has not told you.
• No easy way to pay. If paying means cutting a check or logging into a portal nobody remembers, the invoice slides down the pile.
• No follow-up from you. The single biggest cause. An invoice that no one chases is an invoice that ages. Customers prioritize the suppliers who ask.

You cannot fix what you do not name. The process below removes each of these in turn: it keeps the invoice visible, makes payment one click, surfaces disputes early, and never lets a balance go quiet.

The outstanding invoice collection process

Use this seven-step process on every open invoice. The point is repeatability. The same steps, at the same intervals, on every account.

1. Confirm the invoice is correct and delivered. Before you chase, check the invoice reached the right contact with a valid PO and accurate amounts. Chasing a customer for an invoice they never received, or one with a real error, burns goodwill.
2. Remind before the due date. A short, friendly note three days before the due date catches the customer who simply forgot. This is the cheapest collection you will ever do.
3. Send a first notice in the first week past due. Within three to five days of the due date, send a polite past-due notice. Most invoices that slip get paid here.
4. Escalate at 15 to 30 days. If the balance is still open after two weeks, send a firmer notice that states the amount, the days overdue, and an offer to set up a payment date.
5. Make a call before the final notice. Around 30 days, a short call often unblocks what email cannot. You learn whether it is a dispute, a cash problem, or simple neglect.
6. Send a final notice at 45 to 60 days. State what happens next if the balance stays open: escalation, a hold on new orders, or handoff to collections. Give a firm pay-by date.
7. Escalate to a person or collections. If the final notice passes with no payment and no contact, the account moves to a human decision: a payment plan, a hold, or third-party collections.

Throughout, pause the moment a customer disputes the charge or promises a date. A reminder email no longer helps there, and sending one anyway damages the relationship. For a deeper look at moving the entire metric, see our guide on how to reduce DSO.

Email and call templates to use

Each step needs a message ready to go. Keep every email short, name the exact invoice and amount, and put a payment link in front of the customer.

Due-date reminder

Subject: Invoice [Invoice number] is due [Due date]

Hi [Customer name],

A quick reminder that invoice [Invoice number] for [Amount] is due on [Due date].

You can pay it here: [Payment link]

If you have already sent payment, thank you, and please ignore this note. If anything looks off, reply here and we will sort it out.

Thanks,
[Your name]
[Company name]

When to send: three days before the due date, as a courtesy nudge.

First past-due notice

Subject: Invoice [Invoice number] is now past due

Hi [Customer name],

Invoice [Invoice number] for [Amount] was due on [Due date] and is now past due. It may have slipped through, which happens.

You can settle it here: [Payment link]

If there is a reason the payment is held up, or you need a copy of the invoice, just reply and we will help.

Thanks,
[Your name]
[Company name]

When to send: within the first week past due, before the balance ages further.

Escalation notice

Subject: Action needed: invoice [Invoice number] is [Days overdue] days overdue

Hi [Customer name],

We have not received payment for invoice [Invoice number], totaling [Amount], due on [Due date] and now [Days overdue] days overdue.

Please pay the balance here: [Payment link]

If you cannot pay the full amount right now, reply and let us know. We would rather agree a payment date than let this keep aging.

Regards,
[Your name]
[Company name]

When to send: once the invoice crosses two weeks past due with no response.

Collection call opener

Hi [Customer name], this is [Your name] from [Company name]. I am calling about invoice [Invoice number] for [Amount], which was due on [Due date].

I wanted to check whether you received it and whether there is anything holding up payment on your side.

[Pause and listen.]

If it is simply a matter of scheduling, I can send a payment link right now while we are on the call. If there is an issue with the invoice, tell me and I will get it fixed today.

When to use: around 30 days past due, or any time email has gone unanswered for two cycles.

For a fuller library covering every overdue stage, use our collection email templates.

Escalation paths when customers stall

Not every invoice responds to the standard cadence. When a customer goes quiet or keeps promising without paying, you need a defined path rather than ad-hoc decisions.

• Silence after the final notice. Place a hold on new orders and move the account to a person. A credit hold often unblocks payment faster than any email, because it touches the customer's own operations.
• A dispute appears. Stop the dunning sequence immediately and route the case to whoever owns disputes. Log what is contested, fix or credit it, and only then resume collection on the corrected balance. See managing AR disputes and deductions for the full workflow.
• A broken promise to pay. Once a customer misses a date they set, the friendly assumption is gone. Call, get a firm commitment in writing, and tie it to a consequence.
• A genuine cash problem. Offer a short payment plan rather than letting the full balance default. A scheduled, partial recovery beats a write-off.

The specific timing and tone of overdue escalation deserve their own treatment. For the full overdue workflow with stage-by-stage timing, read how to collect overdue invoices.

Preventing repeat late payers

Collecting the same invoice twice a quarter from the same customer is a process problem, not a one-off. Once a balance is recovered, ask why it aged at all.

• Track who pays late and how late. A simple aging report by customer shows your repeat offenders. They deserve a different default treatment than your reliable payers.
• Fix the root cause. If a customer always pays late because the invoice goes to the wrong contact, fix the contact. If a recurring deduction keeps reappearing, fix the underlying billing error.
• Tighten terms for the worst offenders. Shorter terms, deposits, or partial prepayment for customers who consistently abuse net-30. You are not punishing them, you are pricing in the cost of carrying them.
• Make paying effortless. A payment link in every message and an accepted method the customer actually uses removes the single most common excuse.

Automating collection at scale with Rex

Running this process by hand across a full ledger is where AR teams lose hours, and where invoices fall through. The steps are simple. Doing them consistently on hundreds of open invoices, every day, without missing a touch, is the hard part.

Rex is an AI accounts receivable agent that runs this exact process across every open invoice at once. It watches each invoice, sends the right message at the right age, makes the payment link one click, and escalates tone as the balance ages. When a customer disputes a charge or promises a date, Rex pauses that invoice and routes it to a person, so your team only sees the cases that need a human decision. Nothing ages in silence, and no one is chasing a spreadsheet by memory.

See how Rex runs collections end to end across your whole ledger.