UK Law on Non-Payment of Invoices

If you’ve delivered the work and raised your invoice but the payment still hasn’t landed, you’re not alone. Late and unpaid invoices are one of the most frustrating and disruptive issues for UK small businesses.

The good news? UK law gives you clear tools to encourage prompt payment and recover what you’re owed. With the right processes and a calm, step-by-step approach, you can keep cash flowing and protect client relationships where it makes commercial sense.

In this guide, we’ll unpack non-payment of invoice law in the UK, what to include in your contracts and invoices, and how to escalate from a polite reminder through to legal action-if you need to.

What Does UK Law Say About Unpaid Invoices?

In the UK, late payment for business-to-business (B2B) transactions is governed by the Late Payment of Commercial Debts (Interest) Act 1998 (as amended). This gives you strong rights when a customer doesn’t pay on time.

• Statutory interest: You can generally charge interest at 8% above the Bank of England base rate on overdue B2B invoices unless your contract sets a different “substantial remedy.”
• Fixed recovery costs: You can add a fixed sum to each overdue invoice to cover reasonable debt recovery costs (for example, £40 on debts up to £999.99; £70 for debts between £1,000–£9,999.99; £100 for £10,000+).
• Reasonable additional recovery costs: If your reasonable recovery costs are higher than the fixed sum, you can claim the difference too.

These statutory rights apply automatically to B2B contracts unless you’ve agreed alternative terms that still provide a fair remedy for late payment. For business-to-consumer (B2C) transactions, consumer protection law applies and you’ll need to take a more tailored approach-especially around interest, fees and communications.

Alongside statutory rights, your unpaid invoice will typically amount to a breach of contract. That means you can pursue remedies under contract law-often starting with a formal demand and then moving to court or alternative dispute resolution if payment still doesn’t arrive. For more on claiming losses, it helps to understand compensation for breach of contract in plain terms.

Set Yourself Up For Timely Payment (Before You Invoice)

The best way to deal with unpaid invoices is to prevent them. That starts with strong foundations.

Put Clear Payment Terms In Your Contract

Make sure your client agreement or terms of business sets out:

• When invoices will be issued and due (for example, “14 days from invoice date”).
• Deposits or staged payments, and what happens if a milestone is delayed by the client.
• Late payment consequences (interest, fixed costs and suspension of services).
• Any right to retain title to goods until payment is made (if you supply goods).
• Dispute resolution steps and jurisdiction.

Well-drafted terms reduce ambiguity and give you a clear pathway if payment stalls. If you’re refreshing your templates, don’t forget to check your risk allocations. Many businesses also revisit their limitation of liability provisions at the same time for balance and enforceability.

Issue Legally Compliant Invoices

Invoices should be accurate, easy to understand and include all required information (business name, address, invoice number, VAT details if registered, payment due date, etc.). Errors and missing details are common reasons for delay.

If you need a refresher on what to include, review the basics of UK invoice requirements and make sure your template is up to scratch.

Capture Agreements In Writing

Scope changes and verbal promises can derail payment. Confirm changes by email and keep clean records of approvals and deliverables. As a rule of thumb, assume you’ll need to show what was agreed, when, and by whom-so organise your file like a neat timeline. If you rely on emails to form or vary agreements, it’s worth knowing when emails are legally binding in the UK.

Step-By-Step: How To Deal With Unpaid Invoices

Here’s a practical escalation pathway you can adapt to your business. Tweak the tone to fit your brand and your relationship with the client.

1) Friendly Reminder

When the due date passes, start with a polite nudge. Mistakes happen-your email may have been missed or the approver may be on leave. Keep it short and helpful:

• Attach the invoice again and confirm the due date.
• Offer easy ways to pay and a named contact for queries.
• Give a short grace period (for example, 3–5 working days).

2) Firm Overdue Notice

If there’s no response, send a more formal overdue notice. Reference your payment terms and, where applicable, notify the client that statutory interest and a fixed recovery fee will be applied if payment isn’t received by a stated date.

It’s sensible to copy a second contact (for example, finance@ or the budget holder) in case your day-to-day contact is unavailable.

3) Pick Up The Phone

A short phone call can resolve misunderstandings quickly. Ask whether there’s a query about the invoice or a cashflow issue you can work around. If appropriate, agree a short payment plan in writing. Keep your notes; they’ll be helpful if you need to escalate.

4) Final Demand (Letter Before Action)

When informal steps don’t work, move to a formal “letter before action”. This is a crucial pre‑action step under the Civil Procedure Rules. The letter should set out the debt, what you’ve done to chase it, the legal basis for your claim, the interest and costs you will seek, and a clear deadline for payment.

If you want a structured template and checklist for this stage, our guide to writing a letter before action explains the essentials and common pitfalls.

5) Choose Your Enforcement Route

If payment still doesn’t arrive, you’ll need to decide whether to take legal action, outsource recovery, or write off the debt. Your choice should weigh the amount owed, your evidence, the client’s solvency and the value of the relationship.

• Small Claims Track: For lower-value debts (generally up to £10,000 in England and Wales), you can issue a claim via the Small Claims Track (including through Money Claim Online). It’s designed to be accessible, although you should still prepare carefully.
• Fast Track/Multi-Track: Higher-value or more complex disputes typically move to the County Court or High Court. You’ll want tailored advice before filing.
• Statutory Demand/Winding Up: If the debtor is a company and the debt is undisputed and above threshold, a statutory demand can increase pressure. Use with care-it’s a serious step that can backfire if there’s a genuine dispute.
• Debt Collection/Outsourcing: You can engage a reputable collection agency. In some cases, you may also assign or sell the debt-our guide covers what to consider if you sell a debt to a collection agency.

Before commencing proceedings, make sure you’ve complied with the relevant Pre-Action Protocols (for example, the Debt Claims Protocol). Courts can penalise non-compliance on costs, even if you win.

What Can You Claim When You Sue For Non-Payment?

Your claim will usually include:

• The principal debt (the unpaid invoice amount).
• Interest-either at the contractual rate or statutory rate under the Late Payment Act.
• Fixed and/or reasonable recovery costs under the Late Payment Act (B2B only).
• Contractual costs, if your contract clearly allows recovery of legal costs (note that Small Claims Track limits costs recovery regardless of contract wording).
• Compensation for any additional provable loss flowing from the breach (for example, bank charges)-subject to legal tests of causation and remoteness.

If you need a quick refresher on how courts assess losses, revisit the principles in breach of contract compensation.

Key Legal Points To Keep In Mind

Limitation Periods

Most simple contract claims in England and Wales have a six-year limitation period from the date of breach (usually the due date of the invoice). Don’t leave it too long to act-the longer you wait, the harder it is to gather clean evidence and the more likely the debtor is to become insolvent.

Evidence Wins Cases

Strong paper trails resolve disputes faster. Keep copies of the contract or order, change requests, delivery or completion records, acceptance emails, invoices, reminders and call notes. Screenshots of portals and time-stamped logs can also be persuasive. If details changed during the project, make sure variations were confirmed in writing rather than relying on memory.

Disputed Invoices Need A Different Tactic

If the debtor raises a genuine dispute about quality, scope or timing, pause aggressive recovery tactics and address the dispute on the merits. Offer a short, structured process to review the work, consider a without-prejudice meeting, and document any commercial settlement clearly (for example, a discounted lump sum paid by a fixed date). Where the dispute is entrenched or technical, get advice early.

Consumers vs Businesses

Chasing consumers requires extra care. The Consumer Rights Act 2015 and other consumer protection laws affect your contract terms, interest and communications. This guide focuses on B2B invoices; if you also sell to consumers, make sure your terms and follow-up processes are tailored to comply.

Data Protection Still Applies

If you share customer details with a collections partner or solicitor, you’re processing personal data. Ensure that’s covered by your lawful basis, limit the data to what’s necessary, and put appropriate safeguards in place (for example, a data processing agreement or suitable contractual clauses where required).

Improve Your Contracts And Systems To Prevent Late Payment

A few small changes can dramatically reduce overdue invoices and protect your cash flow.

Strengthen Your Commercial Terms

• Require deposits or milestone payments for larger projects.
• Make delivery contingent on cleared funds (for example, digital keys or final files released after payment).
• Include a clear right to suspend services for non-payment, with a process for resuming work once arrears are cleared.
• Use well-written payment, interest and recovery cost clauses that work alongside statutory rights.

Where your services are recurring, align your contract and billing cadence so customers expect regular payment. If you’re updating your documents, consider a professional Terms of Trade refresh to build these protections in cleanly.

Tighten Your Invoice And Credit Control Process

• Send invoices immediately on completion or at agreed milestones.
• Automate reminders (before due, on due, and shortly after) with a human follow-up if ignored.
• Offer multiple payment options and make them prominent.
• Collect a purchase order where required by larger customers to avoid “no PO, no pay” delays.
• Use statements for regular clients showing all outstanding items.

Your team should know when to escalate and what to say at each step. For higher volumes, consider a standardised Debt Collection Agreement with an external partner so you can switch gears quickly when accounts go overdue.

Be Careful With Contract Variations

Scope creep is a frequent cause of payment disputes. Lock in changes clearly and, where needed, issue a variation order. If your current contract doesn’t handle variations well, it may be time for a tidy-up using a proper contract amendment process so everyone stays aligned.

Frequently Asked Questions About Non-Payment Of Invoices

Can I Charge Interest On Every Overdue Invoice?

In B2B transactions, yes-you can generally claim statutory interest and fixed recovery costs under the Late Payment Act unless your contract provides a different substantial remedy. Just be consistent, notify the customer clearly, and calculate interest correctly.

Do I Have To Send A Letter Before Action?

It’s best practice and often required under the Pre‑Action Protocols. A proper letter before action can prompt payment without court and shows the court you’ve acted reasonably. You can draft it in-house or work with a solicitor; our step-by-step resource on a letter before action covers the key elements.

What If The Client Is Insolvent?

If there are signs of insolvency (returned payments, director resignations, CCJs), act fast. Consider a statutory demand or engage a specialist, but weigh the cost-benefit. You may recover more through a quick discounted settlement than by joining a long queue of creditors.

Are Emails And Purchase Orders Enough To Enforce Payment?

Often, yes-if they capture the essential terms (price, scope, timing) and show clear acceptance. For clarity and risk management, a signed agreement is still best practice, but courts do enforce agreements formed by email chains and POs. See how emails can be legally binding.

Should I Use A Debt Collector Or Go To Court?

It depends on the debt size, your evidence, the debtor’s solvency and your appetite to engage. Agencies can be effective for uncontested debts and take the legwork off your plate. For disputed or higher-value debts, court or solicitor-led action is usually more appropriate. If you’re considering selling the debt outright, check the legal and reputational implications before deciding to sell debt to a collection agency.

Key Takeaways

• In the UK, non-payment of a B2B invoice triggers statutory rights to interest and fixed recovery costs under the Late Payment of Commercial Debts (Interest) Act 1998, alongside your normal contract law remedies.
• Prevention beats cure: clear contracts, accurate invoices and a disciplined credit control process are your best defence against unpaid invoices.
• Escalate in stages: friendly reminder, firm overdue notice, phone call, a proper letter before action, then court/outsourced recovery if necessary.
• Document everything: contracts, variations, delivery, acceptance, reminders and call notes-clean evidence speeds up resolution and improves your prospects if you sue.
• Think commercially: weigh debt size, solvency, relationship and costs before launching proceedings. Sometimes a short, documented settlement is the smartest path.
• Review and improve: build strong payment terms, consider deposits or staged billing, and put a standing arrangement in place with a collections partner for rapid escalation.

If you’re dealing with unpaid invoices or want to tighten your contracts and processes so you’re protected from day one, our team can help. You can reach us at 08081347754 or team@sprintlaw.co.uk for a free, no‑obligations chat.