Overdue Invoices and Statutory Late-Payment Interest: A Tradesperson's Guide

Understanding the Late Payment of Commercial Debts Act

The Late Payment of Commercial Debts (Interest) Act 1998 is a practical tool, not legal theatre. It exists so businesses can’t treat your materials and labour as an interest-free overdraft. If you supply another business — a limited company, a sole trader in trade, or a public authority — and they miss the agreed payment date, you can add statutory interest and a fixed compensation charge to the outstanding invoice. It doesn’t apply to private consumer work. If you’re fitting a bathroom for a homeowner, consumer protections apply and this Act won’t cover you. Keep the business-versus-consumer line crystal clear before you try to apply it.

An invoice becomes overdue on the date payment is contractually due. If your terms say ‘30 days from invoice date’ then payment’s late on day 31. If you agreed payment on completion then, once the job finishes, the clock starts. Public bodies often have their own prompt payment rules — commonly 30 days unless you’ve negotiated otherwise — so check each contract. If terms are unclear you can still charge from when the debt was due but be ready to justify the date you used; poor paperwork is the commonest reason tradespeople lose a chase.

This Act is straightforward to use, but it only helps if you enforce it consistently. Put payment terms on every quote, estimate, invoice and contract. Tell the customer in person and in writing what your payment expectations are. Consistency makes late payment an exception, not an accepted way of doing business. For small firms, cash flow is everything; the Act isn’t complicated, but it won’t fix sloppy admin. Treat it like pricing and contract management — not an occasional tactic when someone won’t answer their phone.

Don’t confuse statutory interest with charging more than your contract allows. If your written terms say ‘no interest’ and the customer signed them, you can still rely on the statutory right to interest on business-to-business debts — the law trumps an ordinary clause that tries to exclude the Act. That said, clarity at the start avoids rows later. I’ve seen roofers lose days arguing dates with builders because the start point for interest wasn’t written down. Write it, say it, and stick to it — that’s how you keep chasing simple and actually get paid.

Calculating Statutory Interest

Statutory interest is straightforward in principle: it’s 8% above the Bank of England base rate applied to the unpaid amount from when the invoice became due until it’s paid. So if the base rate is 1.5% the total annual interest you can charge is 9.5%. That’s an annual rate, so you need to convert it to a daily figure to charge for the actual number of days the invoice is outstanding. Always show which base rate you used and the date you started charging so there’s no mystery. Clear maths avoids most disputes and keeps you looking professional, not petty.

To do the sums: take the unpaid balance, multiply by (Bank base rate + 8) ÷ 100 to get the annual interest, then divide by 365 to get the daily interest. Multiply that daily figure by the actual days overdue. For example — purely hypothetical — a £5,000 invoice with a base rate of 0.5% gives an annual rate of 8.5%. Annual interest would be £425. Divide by 365 to get about £1.16 a day. If it’s 60 days late, that’s roughly £69.60 in interest. Not huge, but it adds up and signals you’re serious about being paid.

Put the calculations on the demand so there’s no arguing. List the invoice number, original due date, days overdue, rate used and the resulting interest figure. Attach a screenshot or link showing the Bank of England rate on the date you started charging; that small bit of evidence saves hours on the phone. If you use accounting software that automates interest, check the settings and ensure it’s applying the correct start date and base rate. Small mistakes suggest you’re disorganised and make customers test you.

Remember interest is compound only if your contract says so — the statutory rate is a simple annual percentage applied day-by-day unless you agree otherwise. In practice, most tradespeople add interest as a single line on a chase invoice rather than recalculating compound interest. That keeps the figures reasonable and the relationship salvageable. The point isn’t to bankrupt someone; it’s to get your invoice paid promptly and to stop late payment becoming standard practice on your jobs.

Fixed Compensation Fees

On top of interest the Act allows a fixed compensation payment to cover the cost of chasing the debt. The tiers are simple: debts under £1,000 attract £40; debts between £1,000 and £10,000 attract £70; and debts over £10,000 attract £100. These sums are set by statute and are intended to cover the administrative cost of chasing payment. They’re not negotiable, and you’re entitled to them as a matter of right when the debt is a business one and is overdue.

Include the compensation charge on your demand alongside the interest calculation and the unpaid invoice. Don’t hide it; state it as the fixed sum the law allows. Tradespeople often leave it off because it feels awkward to add another charge, but it’s lawful compensation for your time and costs. If the other business argues, point out the Act and show the outstanding invoice and due date. Most firms will pay once they know you mean business and your paperwork is straight.

Be aware the fixed amount is a one-off figure per debt, not per reminder. It applies to the unpaid invoice as at the date you are making your claim. If you split one job into several invoices, each invoice can attract its own compensation figure once overdue. That’s why breaking a job into sensible invoices — deposit, progress, final — helps you recover chasing costs without having to rely purely on interest, especially on longer projects.

Finally, don’t ignore the optics. If you’ve got a long-standing customer and you’ve agreed informal extended terms, be pragmatic. Ask for payment and the compensation; if they’re genuinely struggling, agree a short repayment plan in writing and state you’ll waive the compensation on receipt of the first payment. That keeps the relationship while reinforcing that late payment has a cost. Your aim is to be paid, not to create an enemy — but don’t allow repeated lateness to become standard.

How to Claim and Apply Interest

Putting the law into action is simpler than it sounds. First, make sure your invoice and any written contract include clear payment terms — date due, method, and consequences of late payment. When a payment runs late, send a polite but firm reminder the day after the due date. If there’s no response, send a formal demand letter that specifies you are charging statutory interest under the Late Payment of Commercial Debts (Interest) Act 1998, set out your calculation, and add the fixed compensation fee. Keep copies of everything.

Use plain language and numbers. A typical demand should show: invoice number and date, original due date, outstanding amount, days overdue, Bank of England base rate and date used, calculation of interest, and the fixed compensation amount. Add a clear deadline for payment — for example, seven working days — and state the next step if unpaid (small claims or legal action). If you sound procedural and consistent you’ll be taken seriously; if you waffle you’ll be ignored.

Record delivery matters. Email is fine, but keep proof — read receipts, sent folders, or screenshots. For stubborn cases, send a hard copy by recorded delivery and keep the postal receipt. Also keep records of phone calls: date, time, who you spoke to and what was said. These records aren’t just bureaucracy; they build the factual trail that will win disputes. I’ve had jobs where an invoice was paid the moment a recorded delivery letter landed on a director’s desk; some people only react when it’s official.

If you use accounting software, set it to show overdue invoices prominently and to print interest figures correctly. If you’re not confident with the maths, use a simple spreadsheet that shows your workings so you can attach it to the demand. Presenting clear, unarguable figures reduces wriggle room and often brings payment within days. The worst scenario is letting a debt linger because chasing was half-hearted; consistent, properly documented claiming is what brings results.

Practical Steps for Chasing Late Payments

Chasing payment is part of the job — like collecting materials or clearing up. Treat it as such. Have a process: day 1 politely chase, day 7 formal email with interest calculation, day 14 recorded letter, day 21 decide next step (CCJ or solicitor). Stick to the schedule. Tradespeople who pick at chasing only when they remember rarely get paid promptly. Make chasing a short, regular task each week so it doesn’t pile up into a monster.

Phone calls still work. Ring the accounts department or the director if it’s a small firm. Use plain, business language: ‘This invoice is overdue, can you confirm when it will be paid? I am now charging statutory interest and the fixed compensation fee.’ Say it once, clearly. If they give a reason — cashflow, a disputed item — get it in writing and agree a realistic payment date. If they won’t commit, escalate. A simple firm deadline often prompts payment.

Use staged escalation. If reminders and letters fail, use the court route via a money claim online or the small claims track for lower-value debts. For larger sums, instruct a solicitor or consider a statutory demand for a company — but get advice first. The threat of a County Court Judgment (CCJ) often wakes people up; the reality of debt showing on credit files and the prospect of enforcement action makes many businesses prioritise payment. Decide early how far you’re prepared to take it and stick to that plan.

Learn to compromise sensibly. If a good customer is having a genuine short-term issue, agree a short payment plan in writing and ask for a small immediate payment as a sign of intent. If a customer repeatedly pays late with excuses, stop taking the risk — insist on stage payments, deposits, or pay-before-collection terms. Prevention beats cure; change your terms for repeat offenders and you’ll save time and stress chasing in future.

When the Debtor Disputes or Refuses to Pay

Disputes happen. Sometimes they’re genuine — poor work, damage, unfinished tasks — and sometimes they’re excuses to avoid paying. If a dispute is real, sort the complaint quickly and put any agreement to reduce the invoice or fix the work in writing. Do not concede to an oral promise alone. Agree precisely what will be done, by when, and whether interest will still be charged on the undisputed part. If the dispute is spurious, ask for specifics and evidence. Blanket ‘we’re not paying’ lines don’t count as credible disputes under the Act.

If the debtor refuses without a proper dispute, move on to formal action. Start with a Letter Before Action setting a clear payment deadline and warning of court action. For smaller sums use the Money Claim Online service; for larger sums you may need the county court. A CCJ is a practical tool — it converts a dispute into an enforceable judgment and gives you access to enforcement methods like bailiffs or an attachment of earnings. It’s not glamorous, but it works more often than you’d think.

For company debtors, there are harsher steps if they’re wilfully avoiding payment: statutory demand and winding-up petitions are serious. Don’t use them lightly — follow proper legal advice. Insolvency steps can force a limited company to pay or trigger liquidation, which recovers money only in some cases. For sole traders, bankruptcy options exist but are complex and costly. Legal action costs time and money; weigh the likely recovery against the expense before you proceed.

Finally, remember the reputational route. If a business consistently avoids paying, warn other tradespeople and suppliers tactfully through industry networks or trade groups — but be careful not to defame. Better still, learn from the experience: tighten terms, insist on deposits, require stage payments, or refuse work for customers who have previously stiffed you. The best defence is a good offence: stop risky customers before they become bad debts.

Common mistakes

• –Failing to specify payment terms clearly in contracts, leaving room for disputes later.
• –Overlooking the need to calculate and apply interest correctly or consistently.
• –Ignoring overdue payments for too long before taking action, complicating recovery.
• –Not keeping detailed records of all invoicing and recovery communications.
• –Being too aggressive from the onset, damaging client relationships and future work prospects.
• –Neglecting to seek legal advice for large or complex debts, missing out on potential recoveries.
• –Assuming that personal rapport will prevent non-payment without formal agreements.

Questions people ask

Can I charge interest on an overdue invoice to a homeowner?

No, statutory interest under the Late Payment of Commercial Debts Act only applies to business-to-business transactions. For domestic consumers, different rules apply, and it's best to outline your payment terms clearly to homeowners.

What happens if I don't specify terms about late payment in my contract?

If you fail to specify terms, statutory rights still apply for business transactions, but clarity in contracts strengthens your position. Without clear terms, disputes are harder to resolve, so always include payment details in your T&Cs.

How often can I apply interest on an overdue payment?

Interest is calculated daily once the payment is overdue. However, how often you choose to inform the client or take action may vary based on your business practices and client relationship. Regular reminders are advisable.

What if my recovery costs exceed the fixed compensation amount?

The act allows you to claim reasonable additional debt recovery costs if they exceed the fixed compensation amount. Ensure you're keeping detailed records and receipts to support your claim in case of disputes.

Should I involve a solicitor when enforcing late payment rules?

Involving a solicitor can be beneficial, especially for larger debts or challenging clients. Legal input ensures compliance with all applicable laws and can demonstrate to clients that you are serious about debt recovery.