Following Up on Unpaid Invoices

Most invoices settle at the point the client sees a number that grows every day. The key is systematic escalation: polite at first, increasingly specific, and always referencing the contract clause. Here is a ladder you can follow, with templates.

Last reviewed 17 Sep 2026.

The escalation timeline

1Day 1 (day after due date): Polite reminder

Assume it's an oversight. Keep it short, human, and actionable.

Subject: Quick note — Invoice INV-2026-0042 Hi [Name], Invoice INV-2026-0042 for GBP 3,933.00 was due yesterday ([due date]). Just checking in — let me know if there's anything I can clarify or if the invoice needs to be resent to a different address. Thanks, [Your Name]

7Day 7: Statement of account

Still polite, but now factual. Show the ageing and the accruing interest.

Subject: Statement — Invoice INV-2026-0042 (7 days overdue) Hi [Name], Invoice INV-2026-0042 (GBP 3,933.00) was due on [due date] and is now 7 days overdue. Per our agreement (late payment: 8% annual simple interest, 7-day grace), interest begins accruing today. Current status: Principal: GBP 3,933.00 Days overdue: 7 Grace period: 7 days (ends today) Daily interest: GBP 0.86 Accrued interest: GBP 0.00 (grace period) Total due: GBP 3,933.00 Please arrange payment or let me know if there's an issue. Best regards, [Your Name]

14Day 14: Formal notice (quote the clause)

Now you reference the contract, the exact daily rate, and the total including interest. This is the letter that gets escalated to the person who can actually pay.

Subject: FORMAL NOTICE — Invoice INV-2026-0042 (14 days overdue) Dear [Name], Invoice INV-2026-0042 for GBP 3,933.00 was due on [due date] and is now 14 days overdue. Under Clause 7.2 of our agreement dated [date]: “Late payments carry 8% annual simple interest after a 7-day grace period. A fixed administrative fee of GBP 40 applies to any overdue invoice.” As of [today's date]: Principal outstanding: GBP 3,933.00 Days overdue: 14 Grace period: 7 days Billable days: 7 (14 overdue, less 7 grace) Daily interest (8%/365): GBP 0.86 (3,933.00 x 0.08 / 365) Simple interest accrued: GBP 6.03 (0.86 x 7) Administrative fee: GBP 40.00 --------------------------------------- Total now due: GBP 3,979.03 Interest continues to accrue at GBP 0.86 per day until payment is received. Please remit payment within 7 days (by [7 days from today]) to avoid further escalation. Payment details: [Bank details from invoice] Regards, [Your Name]

30Day 30: Pause further work

If the contract allows (and it should), pause work. This is often what finally triggers payment.

Subject: WORK PAUSED — Invoice INV-2026-0042 (30 days overdue) Dear [Name], Invoice INV-2026-0042 (GBP 3,933.00) is now 30 days overdue. Days overdue: 30 Billable days: 23 (30 overdue, less 7 grace) Daily interest: GBP 0.86 Simple interest accrued: GBP 19.83 (0.86 x 23) Administrative fee: GBP 40.00 ---------------------------------------- Total due: GBP 3,992.83 Per Clause 7.3 of our agreement: “Work may be paused on any account overdue by more than 30 days.” Effective immediately, all work on [Project Name] is paused. This includes: • [Specific deliverable 1] • [Specific deliverable 2] • [Any scheduled meetings/calls] Work will resume within 1 business day of cleared payment. To resolve: pay the outstanding GBP 3,992.83 to the account details below and confirm once sent. Regards, [Your Name]

Key principles

Always reference the invoice number. Makes it trivial for them to find and pay.
Quote the contract clause. Moves it from “you're asking nicely” to “this is what we agreed”.
Show the maths. Use the Late Fee Estimator to generate the exact figures. A specific number (GBP 6.03) is far more effective than “interest may be charged”.
Escalate the recipient. Day 1 → your contact. Day 7 → your contact + CC their manager. Day 14 → finance/accounts payable. Day 30 → director/owner.
Keep a paper trail. Every email is evidence if you need to pursue formally.

What if they dispute the invoice?

If they raise a genuine query (wrong amount, missing PO, wrong details):

Acknowledge within 24 hours.
Fix the error and re-issue with a new invoice number (referencing the old one).
Reset the due date from the corrected invoice date.
Interest only accrues from the new due date.

If the dispute is vexatious (they're stalling), the clock keeps ticking on the original invoice. State this in writing.

Payment plans

If they genuinely can't pay in full, offer a plan — but formalise it:

Written agreement (email is fine) with specific dates and amounts.
Interest continues to accrue on the declining balance.
Missed instalment = entire balance immediately due.
Work remains paused until the plan is signed.

Use the Late Fee Estimator to calculate what interest is fair if the balance is cleared over three months.

When to involve a third party

Letter before action (LBA): Formal legal letter (you can write it yourself or use a solicitor). Often the final nudge.
Small claims / money claim online: UK: Money Claim Online (up to GBP 10k). US: Small claims court (limits vary by state). EU: European Small Claims Procedure (up to EUR 5,000).
Statutory demand (UK): For debts > GBP 750 (company) or > GBP 5,000 (individual). Precursor to winding-up/bankruptcy.
Debt collection agency: Typically 10–25% of recovered. They chase; you get the rest.

Prevention: the best follow-up is the one you don't need

Get the PO number before you start.
Send the invoice the day the work is done (not a week later).
Put the due date as a calendar date, not “Net 30”.
State late-payment terms on every invoice.
Use the Invoice Generator — it prompts for all of the above.

Try the estimator

Open the Late Fee Estimator. Enter the principal, rate, days overdue, grace period, and flat fee — it generates the exact figures for your formal notice.

This guide provides practical escalation templates. It is not legal advice. Debt recovery procedures, limitation periods, and enforcement options vary by jurisdiction. Take advice before pursuing formal action.

Run the numbers

Late Payment Fee Estimator - works both ways round, and shows the arithmetic it used underneath.

Open Late Payment Fee Estimator