Past Due Invoice: Templates, Escalation Paths, and What Actually Works

What Is a Past Due Invoice?

A past due invoice is a receivable that has aged beyond the contractual payment date without settlement. If the terms were Net 30 and day 31 passes with no payment posted, the invoice is past due.

One missed payment is usually noise. Two consecutive invoices aging past due signals something worth investigating. Three or more tells you the relationship has changed and your credit file needs an update.

How Past Due Invoices Differ from Overdue Invoices

The terms get used interchangeably. Practically: past due means payment not received by the due date (days 1–30+). Overdue typically implies escalation is already underway. Track both the count of past due invoices per account and the days past due (DPD) per invoice. Both belong on your collections dashboard, not just DSO.

Why Invoices Go Past Due

Administrative delays: The customer received the invoice but lost it, routed it wrong, or has an approval backlog. These resolve with one phone call.

Cash flow pressure: The customer is managing payables by prioritizing certain vendors. Customers who pay specific suppliers on time while stretching others are signaling counterparty priority. You want to be at the top of that list.

Disputed invoices: The customer has a legitimate or manufactured objection. Disputes need resolution before the invoice is collectable. Dunning letters do not close disputes.

Credit deterioration: The customer's financial position has weakened. They are not slow-paying because of admin friction—they are slow-paying everyone. This is the version that leads to write-offs. HighRadius and Bectran build collections workflows around the first three categories. The fourth requires monitoring outside the AR ledger: public filings, payment behavior across the portfolio, trade reference patterns. Most AR automation tools do not surface this.

Past Due Invoice Templates

Day 1–7: Reminder Email

Subject: Invoice [#] Due [Date]—Friendly Reminder

Hi [Contact Name],

Invoice [#] for [amount] was due on [date]. If you have questions or need a copy, reply here. If payment is already in process, no action needed on your end.

[Your name]

Keep it short. Tone should be matter-of-fact, not apologetic.

Day 8–15: Follow-Up

Subject: Re: Invoice [#]—Still Outstanding

Hi [Contact Name],

Following up—invoice [#] for [amount] is now [X] days past due. Let me know if anything is holding up payment. If you are working through a dispute or need updated remittance information, I can help now.

[Your name]

Day 16–30: Phone Call

Email alone stops working here. Call AP directly. If you cannot reach AP, call the buyer who originated the order. The message: Invoice [#] for [amount] is now [X] days past due. We need to confirm a payment date today to keep the account current.

Document who you spoke with, what they said, and any commitment date they gave. A verbal commitment with no follow-through is escalation criteria.

Day 31–60: Formal Demand Letter

The letter goes to the AP director or CFO, not the day-to-day buyer. CC your AR manager. See: How to Write a Demand Letter for Payment.

Day 61+: Escalation Decision Point

At 60+ days, make a decision: hold additional shipments, reduce or freeze the credit line, transfer to a collections agency, or pursue legal remedies. Collections agencies typically take 25–50% of recovered amounts. Legal action adds cost and relationship damage. The right answer depends on the balance, the relationship, and your read on the customer's financial position.

Credit teams that monitor customer financials continuously catch the deterioration behind 61+ day invoices before it compounds. By day 60, the financial signals were usually visible 3–6 months earlier.

Building a Past Due Invoice Policy

A solid collections policy specifies:

• Escalation thresholds: When does the AR analyst pass to the AR manager? When does the AR manager escalate to legal or collections?
• Hold thresholds: At what DPD or outstanding balance do you stop shipping? Most B2B companies set a hold at 60–90 DPD or two consecutive unpaid invoices, whichever comes first.
• Dispute resolution SLA: When a customer disputes an invoice, who owns resolution and within what timeframe?
• Credit review triggers: An account with two or more past due invoices in a quarter should trigger a credit review, not just a collections call.
• Write-off thresholds: At what point do you write off a balance? Define this before the decision is emotional. Most B2B companies write off at 180+ DPD after collections exhaustion.

How DSO Connects to Past Due Invoice Volume

DSO is the aggregated lag across all receivables. When past due invoice count rises, DSO follows—usually with a 30–45 day lag. By the time DSO shows the problem, the invoices behind it are already 60+ days old.

DSO is a trailing metric. Past due invoice count, by account and by aging bucket, is the leading indicator. Track both; act on the leading number.

See: DSO by Industry Benchmarks | DSO Formula and Calculation Guide | Dunning Letter Guide

FAQ

What is the difference between a past due invoice and a delinquent invoice?

A past due invoice is any invoice beyond its due date. Delinquent typically applies once the invoice has entered formal escalation or a collections agency. The distinction matters for reporting classification and priority.

When should you stop extending credit to a customer with past due invoices?

When two or more invoices are consecutively unpaid, or when an account reaches 60 DPD without a confirmed payment plan, freeze credit until the balance clears before releasing additional orders.

Can a customer dispute a past due invoice?

Yes. Disputed invoices have different treatment than neglected ones. The dispute needs resolution before the invoice is collectable. Document all disputes in writing.

How do past due invoices affect DSO?

Directly. A cluster of accounts in the 60–90 DPD bucket moves average DSO materially. Monitor past due count by aging bucket weekly, not just at month-end.

What happens if a customer never pays?

After collections exhaustion and the write-off threshold is crossed, the balance becomes a bad debt expense. Legal recovery may be viable depending on balance size and jurisdiction. Factor in collection probability and relationship value before pursuing litigation.