Overdue Invoice Email & Letter Templates: Past Due Invoice Letters for 30, 60 & 90 Days

Regardless of whether you are writing a 14-day friendly reminder or a 90-day final notice, every overdue invoice letter must contain the same core elements. Missing any one of these weakens the letter and, if you later take legal action, may slow down the process.

The Complete Checklist

1. Invoice number and original invoice date — Reference the specific invoice. If there are multiple unpaid invoices, list each one separately with its number, date, and amount.
2. Original due date and exact number of days overdue — State this explicitly. "Your invoice was due on 1 February and is now 30 days overdue" is far clearer than "your invoice is past due."
3. Amount outstanding including any accrued late fees — Break the total down: original invoice amount, late fee accrued, total now owed. Never leave the client to calculate it themselves.
4. A log of all previous contact attempts — From the 45-day stage onward, list every prior contact: date sent, method (email/phone/letter), and whether you received a response. This creates a documented paper trail that demonstrates good faith if you later file a claim.
5. A specific new payment deadline — Not "as soon as possible" or "at your earliest convenience" — a real calendar date. "Please arrange payment by Friday 28 March 2026."
6. Full payment instructions with no friction — Bank name, account number, sort code or routing number, and reference. Or a direct payment link. If the client has to ask how to pay, you have created an unnecessary barrier.
7. Consequence of non-payment, scaled to the stage — 14–30 days: late fees will be applied. 45–60 days: you will refer to a collections agency. 90 days: you will commence legal proceedings. State it plainly. Vague consequences are ignored.
8. A dispute resolution path — Even at the final notice stage, give the client a way to raise a legitimate query in writing. This demonstrates good faith and prevents the client later claiming they had no opportunity to respond.
9. Your full contact details and the date the letter was written — Name, business name, address, phone, and email. For formal letters sent by post, the date on the letter matters for any legal timeline.

Keep the tone factual throughout. Emotional language — phrases like "I am extremely disappointed" or "this is unacceptable" — undermines your professional standing and can complicate dispute resolution. UK businesses sending overdue letters can also reference their right to charge statutory interest under the Late Payment of Commercial Debts Act 1998. For earlier-stage email reminders, see 12 copy-paste reminder email templates.

Both formats serve a purpose — and the right choice depends on how overdue the invoice is and how much is at stake. Using the wrong format at the wrong time either wastes money (registered post when a quick email would have resolved it) or weakens your legal case (email-only when a physical paper trail was required).

When Email Is Sufficient

Email is appropriate for the first two stages — 14 days and 30 days overdue. It is fast, free, creates a timestamped record, and the majority of late payments at this stage are resolved without any further escalation. Email also makes it easy for the client to click a payment link and settle immediately.

Make sure your email client records sent messages with a timestamp, and keep a screenshot or export of the sent email. If you use InvoiceGrid, the reminder log tracks every contact attempt automatically.

When to Send a Formal Printed Letter

At 30 days overdue and certainly by 45 days, add a formal printed letter to your process. A printed letter on headed paper, sent by recorded or registered post, carries significantly more legal weight than an email for several reasons:

• Proof of delivery — Recorded post gives you a signed receipt confirming the letter was received. Email delivery receipts are unreliable and courts treat them sceptically.
• Psychological weight — A physical letter on headed paper signals seriousness in a way an email does not. Clients who have been ignoring emails often respond to a letter within days.
• Legal evidence — If you file in small claims court, you will need to show evidence that you gave the debtor reasonable opportunity to pay. A documented posting record is far more convincing than a thread of ignored emails.
• Formal tone cues — Courts, debt collection agencies, and solicitors use formal letters. Matching that format signals to the client — and any third party who later reviews the correspondence — that you understand the process.

The Stage-by-Stage Format Rule

At the 60-day and 90-day stages, send both formats on the same day and note in the email that a formal letter has also been posted. This maximises the chance of contact and creates a complete dual-channel paper trail.

At 14 days, the tone is friendly and assumes a straightforward oversight. Many late payments at this stage are genuinely administrative — a missed approval, a forwarding issue, a bank holiday delay. A short, non-confrontational email resolves the majority of these without any further escalation.

Send by email only. No post required at this stage.

Subject: Invoice #[NUMBER] — Payment Overdue | Quick Follow-Up

Dear [Client Name],

I hope you are well. I wanted to follow up on Invoice
#[NUMBER] for [AMOUNT], which was due on [ORIGINAL DUE
DATE] and is now 14 days overdue.

This may simply be an oversight — these things happen.
Could you please arrange payment or let me know when to
expect it?

Payment details:
[Bank name / sort code / account number]
[Or: payment link]
Reference: Invoice #[NUMBER]

If there is any query or issue with the invoice, I am
happy to discuss it — just reply to this email.

Many thanks,
[Your Name]
[Your Business Name]
[Phone / Email]

If you receive no reply within five business days, follow up with a brief phone call. Note the date, time, and outcome of the call in your payment log. Then proceed to Stage 2 at 30 days. For softer email reminders at this stage, see the complete email reminder guide.

At 30 days, the letter becomes formally structured. It references the previous contact attempt, states the amount with any applicable late fee, and sets a specific new deadline. The tone shifts from collegial to professional-formal — but it still assumes the client intends to pay and leaves room for easy resolution.

Send by email. Consider also sending a printed copy on headed paper by first-class post.

Subject: Invoice #[NUMBER] — 30 Days Overdue | Payment Required by [NEW DATE]

Dear [Client Name],

I am writing to follow up on Invoice #[NUMBER] for
[AMOUNT], which was due on [ORIGINAL DUE DATE] and is
now 30 days overdue.

I contacted you regarding this invoice on [PREVIOUS
CONTACT DATE] and have not yet received payment or a
response.

I understand that delays can occur, and I would be
grateful if you could arrange payment of [AMOUNT] by
[SPECIFIC DATE — 7 DAYS FROM NOW].

Payment details:
[Bank name, account number, sort code / routing number]
[Or: payment link]
Reference: Invoice #[NUMBER]

Please note that a late fee of [RATE/AMOUNT] is
applicable as of [DATE] per our agreed payment terms.
If payment is received by [NEW DATE], I am happy to
waive this fee.

If you have any query regarding this invoice or wish
to discuss a payment arrangement, please contact me in
writing by [DATE].

Kind regards,
[Your Name]
[Your Business Name]
[Address]
[Phone / Email]
[Date]

The offer to waive the late fee if they pay by the new deadline is a useful tool at this stage — it gives the client a financial incentive to act now rather than ignore the letter. Remove this offer from the 45-day template onward. Track all follow-ups with InvoiceGrid's reminder generator.

At 45 days, the friendly tone is dropped. This letter states the complete contact history, applies the late fee without the option to waive it, sets a shorter deadline, and names a specific consequence for non-payment. Send by both email and recorded post.

Send by email AND recorded/signed-for post on the same day. Keep the postal receipt.

Subject: Invoice #[NUMBER] — 45 Days Overdue | Firm Payment Notice

Dear [Client Name],

RE: Overdue Invoice #[NUMBER] | Original Amount: [AMOUNT]
    Original Due Date: [DATE] | Days Overdue: 45

I am writing for the third time regarding the above
invoice, which remains unpaid. My previous contacts
were:

  — [CONTACT METHOD]: [DATE 1] — no response
  — [CONTACT METHOD]: [DATE 2] — no response

The outstanding balance, including the late fee of
[LATE FEE] applied per our agreed payment terms, is
now [TOTAL AMOUNT].

I require payment of [TOTAL AMOUNT] by [DATE — 10 DAYS
FROM NOW].

Payment details:
[Bank name, account number, sort code / routing number]
[Or: payment link]
Reference: Invoice #[NUMBER]

If this invoice is in dispute, you must notify me in
writing by [DATE — 5 DAYS FROM NOW] with specific
details of your query. Failure to pay or respond in
writing by the deadlines above will result in referral
of this debt to a collections agency.

This letter has been sent by both email and recorded
post.

Regards,
[Your Name]
[Your Business Name]
[Address]
[Date]

The phrase "third time" and the explicit list of previous contacts are not for the client's benefit alone — they are for your benefit if you later file a claim. Courts want to see that you made reasonable attempts to resolve the matter before escalating. Logging all contacts in a payment tracker means you can pull this history in seconds. See invoice follow-up phone call scripts for what to say if you make a call at this stage.

At 60 days, this is a formal demand letter. The language is unambiguous, the consequence is specific, and the deadline is short. There is no offer of flexibility and no room for misinterpretation. Send by email and recorded/registered post and note in the email that a physical copy has been posted.

Send by email AND recorded/registered post. State both in the letter itself.

Subject: Urgent: Invoice #[NUMBER] — 60 Days Overdue | Action Required

Dear [Client Name],

RE: FORMAL DEMAND — Invoice #[NUMBER]
    Original Amount: [AMOUNT] | Due Date: [DATE]
    Days Overdue: 60

I am writing to formally demand payment of the
outstanding balance on the above invoice.

Despite written contact on the following dates, this
invoice remains unpaid:

  — [DATE 1]: [Method] — no response
  — [DATE 2]: [Method] — no response
  — [DATE 3]: [Method] — no response

As per our agreed payment terms, a late fee of
[LATE FEE AMOUNT/RATE] has been applied from
[DATE LATE FEE STARTED].

Amount breakdown:
  Original invoice: [AMOUNT]
  Late fee accrued: [LATE FEE AMOUNT]
  TOTAL NOW DUE:    [TOTAL]

You are required to pay [TOTAL] by [DATE — 14 DAYS
FROM NOW].

Payment details:
[Bank name, account number, sort code / routing number]
[Or: payment link]
Reference: Invoice #[NUMBER]

If this invoice is in dispute, you must contact me in
writing by [DATE — 5 DAYS FROM NOW] with specific
grounds for your dispute.

If payment or a written dispute is not received by
[DEADLINE], I will refer this debt to a collections
agency and/or commence legal proceedings without
further notice.

Yours faithfully,
[Your Name]
[Your Business Name]
[Full Address]
[Date]

Sent by: Email and Recorded Post

Note the shift to "Yours faithfully" — the correct formal closing for UK letters when writing in an official capacity, signalling this is now a legal matter. In US correspondence, "Sincerely" or "Respectfully" is appropriate. For collection-specific language at this stage, see collection email templates for past due invoices.

At 90 days, this is your last formal step before legal action. Keep it short and unambiguous — state the facts, the complete contact history, the total owed, and the exact consequence. A brief, factual final notice carries more weight than a long, emotional one.

Send by email AND recorded post. Keep the delivery receipt — you will need it if you file a claim.

Subject: FINAL NOTICE: Invoice #[NUMBER] — Legal Action Notice

Dear [Client Name],

RE: FINAL NOTICE BEFORE LEGAL PROCEEDINGS
    Invoice #[NUMBER] | Total Outstanding: [AMOUNT]

Despite written communications on [DATE 1], [DATE 2],
[DATE 3], and [DATE 4], Invoice #[NUMBER] for [ORIGINAL
AMOUNT] (original due date: [ORIGINAL DUE DATE]) remains
unpaid. This invoice is now 90 days overdue.

Full contact history:
  — [DATE 1]: [Method]
  — [DATE 2]: [Method]
  — [DATE 3]: [Method] — recorded post, delivered [DATE]
  — [DATE 4]: [Method] — recorded post, delivered [DATE]

Total amount now outstanding (including accrued late
fees): [TOTAL INCLUDING LATE FEES]

This letter is formal notice that unless the outstanding
balance of [TOTAL] is received by [DATE — 7 DAYS FROM
NOW], I will commence legal proceedings without further
notice.

This may include:
  — Filing a claim in small claims court
  — Engaging a debt collection agency
  — Reporting the outstanding debt to credit reference
    agencies

To resolve this matter immediately, transfer [TOTAL] to:
[Payment details]
Reference: Invoice #[NUMBER]

If you believe there is a legitimate dispute regarding
this invoice, you must contact me in writing within
48 hours of receipt of this letter.

Yours sincerely,
[Your Name]
[Your Business Name]
[Your Full Address]
[Date]

This letter has been sent by email and recorded post.

If the 90-day final notice goes unanswered, proceed exactly as stated. See: Can You Take a Client to Small Claims Court? and What Happens If an Invoice Is Never Paid?

14 Days Overdue

• "Invoice #[NUM] — Payment Overdue | Quick Follow-Up"
• "Following Up: Invoice #[NUM] for [Amount] — Due [Date]"
• "Friendly Reminder: Invoice #[NUM] — [Amount] Outstanding"

30 Days Overdue

• "Invoice #[NUM] — 30 Days Overdue | Payment Required by [Date]"
• "Payment Overdue: Invoice #[NUM] for [Amount] | Action Required"
• "Second Notice: Invoice #[NUM] — [Amount] Outstanding"

45 Days Overdue

• "Invoice #[NUM] — 45 Days Overdue | Firm Payment Notice"
• "Third Notice: Invoice #[NUM] — [Amount] | Deadline [Date]"
• "Invoice #[NUM] — Late Fees Now Applied | Response Required by [Date]"

60 Days Overdue

• "Urgent: Invoice #[NUM] — 60 Days Overdue | Immediate Action Required"
• "Invoice #[NUM] — 60 Days Past Due | Formal Demand for Payment"
• "FORMAL DEMAND: Invoice #[NUM] — [Amount] | Action Required by [Date]"

90 Days Overdue

• "FINAL NOTICE: Invoice #[NUM] — Legal Action Notice"
• "Notice of Intended Legal Proceedings — Invoice #[NUM]"
• "Invoice #[NUM] — Final Notice Before Debt Recovery Action"

Always include the invoice number and amount in the subject line. Specific subject lines are harder to dismiss and easier to find later. For a full library of templates see: professional reminder templates and 25 polite payment reminder subject lines.

Most overdue invoice letters fail not because they are too aggressive or too passive, but because they make one or more of these structural errors. Each mistake either reduces the psychological impact of the letter or weakens your legal position if you escalate.

You have sent four or five letters, including a formal final notice by recorded post. The deadline has passed. Still no payment, no dispute, no response. At this point, you have four main paths — and they are not mutually exclusive.

Option 1: Small Claims Court

Small claims is designed for exactly this situation — straightforward debt recovery without the cost of a solicitor. In England and Wales, claims up to £10,000 go to the Small Claims Track. In the US, limits vary by state (typically $2,500–$25,000). The process is accessible to individuals and small businesses, and filing fees are low relative to the amounts typically at stake.

Your documented paper trail — invoices, payment terms, every letter and email, postal receipts — is your case. An invoice chase log that timestamps every follow-up makes this documentation automatic. Courts award the debt plus court fees and, in the UK, statutory interest. Filing itself often prompts immediate payment, because the client now faces a county court judgment (CCJ) on their credit record if they do not settle.

For a step-by-step guide see: Can You Take a Client to Small Claims Court for an Unpaid Invoice?

Option 2: Send a Formal Demand Letter

A demand letter is a step above the overdue notice — it is a formal legal document that states the debt, the legal basis for the claim, and a final deadline before you file. In the UK this is called a "Letter Before Action" (LBA) and courts require it before a claim can be filed. In the US, it functions as evidence of good faith effort.

A demand letter is distinct from the overdue letter templates above — it references specific legal statutes, may mention your intention to claim costs, and is often written on a solicitor's letterhead or in a format that mirrors one. See: How to Write a Demand Letter for an Unpaid Invoice.

Option 3: Debt Collection Agency

A collections agency takes over the recovery process in exchange for a percentage of the recovered amount — typically 15–40%, varying by agency and debt age. You transfer the debt to them and, if they recover it, you receive the balance minus their fee. No upfront cost in most cases.

The main consideration: once you engage a collections agency, the client relationship is almost certainly over. For high-value ongoing clients, exhaust the legal route first. For lower-value debts from clients you do not wish to continue working with, a collections agency is often the most time-efficient path.

Option 4: Write Off as Bad Debt

If the amount is small, the client has no assets, or the legal and collections costs exceed the debt value, writing off the invoice as a bad debt is a legitimate business decision. In most jurisdictions you can claim bad debt relief for VAT already paid (UK) or deduct the bad debt as a business expense (US). Keep all your documentation — the write-off does not erase the legal debt, and if the client resurfaces you can reassert the claim.

See also: What Happens If an Invoice Is Never Paid? and How to Protect Yourself from Non-Paying Clients.

In the UK, the Late Payment of Commercial Debts (Interest) Act 1998 gives you the automatic right to claim statutory interest and fixed recovery costs on overdue B2B invoices — even if your contract contains no late fee clause. This applies to invoices between businesses (not consumer sales).

What You Can Claim

• Statutory interest: 8% above the Bank of England base rate, accruing daily from the day after the payment due date.
• Fixed recovery costs: £40 for invoices up to £999.99 · £70 for £1,000–£9,999.99 · £100 for £10,000 and above.
• Reasonable debt recovery costs beyond the fixed amounts if your actual recovery costs exceed them.

You do not need to include these rights in your contract — they apply automatically. However, referencing the Act in your letter signals to the client that you know your legal position.

UK Overdue Invoice Letter Template (Late Payment Act)

For use at 30+ days overdue on B2B invoices. Adapt for 60 and 90-day escalation by increasing the tone.

Subject: Overdue Invoice #[NUMBER] — Notice of Statutory Interest Under the Late Payment of Commercial Debts Act 1998

Dear [Client Name],

RE: Invoice #[NUMBER] | Amount: £[ORIGINAL AMOUNT]
    Original Due Date: [DATE]

I am writing to notify you that the above invoice is
now [X] days overdue.

Under the Late Payment of Commercial Debts (Interest)
Act 1998, I am entitled to claim statutory interest at
8% above the Bank of England base rate on the
outstanding balance, accruing from the day after the
original due date.

Statutory interest to date:      £[CALCULATED AMOUNT]
Fixed recovery costs (per Act):  £[40/70/100]
Total now outstanding:           £[TOTAL]

I would be grateful if you would arrange payment of
£[TOTAL] by [DATE — 7 DAYS].

Payment details:
Bank: [Bank Name]
Sort Code: [XX-XX-XX]
Account Number: [XXXXXXXX]
Reference: Invoice #[NUMBER]

If you have any query regarding this invoice, please
contact me in writing within 5 working days.

If payment is not received by [DATE], I reserve the
right to refer this matter for debt recovery without
further notice.

Yours sincerely,
[Your Name]
[Business Name]
[Address]
[Date]

Note: To calculate the exact statutory interest amount: (Outstanding amount × (0.08 + current BoE base rate)) ÷ 365 × days overdue. Use the invoice penalty calculator to get the precise figure, then state it explicitly in the letter.

Key Differences from US Late Payment Letters

• UK statutory interest applies automatically — you don't need a late fee clause in your contract
• Fixed recovery costs (£40–£100) are a legal entitlement, not a negotiated fee
• For UK letters going to court, use the term "Letter Before Action" (LBA) — courts expect this before a claim is filed
• Small claims in England and Wales: claims up to £10,000 go to the Small Claims Track; Scotland uses the Simple Procedure for claims up to £5,000

• Past Due Invoice Email: 7 Templates That Get You Paid — email-specific templates for 7, 14, 30, and 60+ days past due.
• Collection Email for Past Due Invoices — when standard reminders fail, switch to formal collection language.
• Payment Reminder Email Templates — 12 templates for before-due to final notice in 4 tones.
• Demand Letter for Unpaid Invoice — the formal written demand that comes before legal action.
• Chasing Clients for Payment — complete guide to the full follow-up process from first reminder to final notice.
• Protect Yourself from Non-Paying Clients — contract terms, deposit structures, and processes to prevent late payment.