How to handle a dispute over an overdue invoice

An overdue invoice is frustrating enough, but when a client disputes it, the situation becomes far more complex. Suddenly, you’re not just chasing a payment; you’re defending the quality of your work, the accuracy of your admin, and even your honesty. This guide provides a practical, step-by-step process for UK small businesses and freelancers to handle disputed invoices professionally, protect their cash flow, and preserve client relationships where possible. We’ll cover everything from simple misunderstandings to deliberate delay tactics and when to escalate.

First, Triage the Dispute: What's the Real Problem?

Before you fire off an angry email, take a breath. The single most important step is to understand the type of dispute you’re facing. Getting defensive or making assumptions will only make things worse. Broadly, disputes fall into three categories.

Category 1: Genuine Misunderstanding or Error

This is the most common and easiest type of dispute to resolve. It's usually not a reflection on you or your work, but a simple administrative breakdown somewhere in the chain.

• "We never received the invoice." This is a classic. It could be a genuine technical issue (your email went to their spam folder), a human error (you used an old contact address), or a problem with their internal mail-forwarding.
• "The invoice has an error." The client might point out a wrong Purchase Order (PO) number, an incorrect address, a miscalculation, or a mistake in the VAT breakdown. Large organisations in particular have rigid accounts payable processes and will reject invoices for the smallest error.
• "The person who handles this has left." In larger companies, staff turnover can mean your invoice is sitting in a departed employee's inbox with no one aware of it.

These are problems of communication and process, not of substance. They are usually resolved quickly and amicably.

Category 2: Dissatisfaction with the Work or Service

This is a more serious category of dispute. The client is not questioning the invoice itself, but the underlying value of what you delivered.

• "The work was not completed to the agreed standard."
• "You didn't deliver everything in the scope of work."
• "The project was delivered late and it caused us problems."

Here, the client is linking payment to their perceived quality of the service. These disputes require careful handling, as they can damage your reputation and professional relationship if managed poorly.

Category 3: Deliberate Delay Tactic

This is the most frustrating category. The client has no genuine issue with the invoice or the work; they are simply trying to delay payment because of their own cash flow problems. They invent excuses to buy themselves time.

Signs of a deliberate delay tactic include:

• Vague, unsubstantiated complaints: "I'm just not happy with it" without providing any specific examples.
• Shifting goalposts: They raise a new, different issue every time you resolve the previous one.
• Ignoring communication: They go silent when you ask for specific details about their complaint.
• Classic excuses: "The director who signs cheques is on holiday," or the infamous, "The cheque is in the post."

Identifying which category the dispute falls into will dictate your entire strategy for resolving it.

The Immediate Response: Acknowledge and Investigate

Regardless of the reason for the dispute, your first response should always be professional, calm, and prompt.

1. Acknowledge Immediately: Send a brief email confirming you have received their message and are looking into the matter. Something as simple as, "Thanks for letting me know. I'm looking into this now and will come back to you within 24 hours," is perfect. This shows you are taking their concern seriously and de-escalates any initial tension.
2. Investigate Thoroughly: Now, do your homework based on the dispute category.
   • For "Invoice Not Received": Don't just forward the old email. Send a fresh one with the invoice attached as a PDF. In the body of the email, politely state, "Resending the attached invoice [Invoice Number] for your attention. Please can you confirm you've received this safely?" This creates a new, clean paper trail. This is where a clear audit trail becomes invaluable. If you're manually sending emails, you might have to dig through your sent items. An automated system like InvoiceReminder keeps a log of every reminder sent, which can help establish a timeline if a client claims they were never contacted.
   • For "Invoice Error": Check your own records against their claim. Review the PO, your original quote, and your accounting software. If you have made a mistake, own it immediately. Apologise, issue a formal credit note for the incorrect invoice, and raise a new, correct invoice. A quick and humble correction builds far more trust than a defensive denial.
   • For "Dissatisfaction": This requires more digging. Gather all relevant documents: the signed contract or proposal, the scope of work document, all email correspondence, project management records, and any evidence of client sign-off or approval at different stages. You need to build a complete picture of the project from start to finish before you respond.

How to Resolve Scope and Quality Disputes

This is where most businesses struggle. The key is to move the conversation from subjective feelings ("I'm not happy") to objective facts ("The contract specified X, and we delivered Y").

Step 1: Get It In Writing

If the client's complaint is vague, your first job is to get specifics. Politely ask them to outline their concerns in writing.

Example phrase: "To make sure I fully understand and can address your concerns properly, could you please email me a list of the specific parts of the project that didn't meet your expectations?"

This serves two purposes. First, it forces the client to articulate their problem clearly. Often, the act of writing it down can make them realise their complaint is weak. Second, it protects you. If the dispute escalates, you have a written record of their specific issues, preventing them from inventing new ones later.

Step 2: Compare to the Agreement

Once you have their specific points, compare them one-by-one against your signed contract, proposal, and scope of work.

• Is their request part of the original scope? If they are complaining about something that was never agreed upon, you can gently point this out. "The issue you've raised regarding [feature] wasn't part of the original scope of work we agreed. We'd be happy to quote for that as a separate piece of work."
• Did they sign off on the work? If you have emails or project management logs showing they approved the very thing they are now complaining about, you can refer back to them. "I've checked my records, and it looks like we received sign-off on the design mock-ups on [Date]. I've attached the email for your reference."

Step 3: Propose a Solution

Based on your investigation, decide on a course of action.

• If their claim has merit: If you genuinely missed something or made a mistake, the best course of action is to fix it. Offer to complete the outstanding work or rectify the error at no extra charge. If fixing it isn't possible, you might offer a small, specific discount on the invoice as a goodwill gesture. Frame it as a solution, not an admission of total failure.
• If their claim is baseless: Calmly and professionally present your evidence. Lay out the facts, reference the contract, and show the sign-offs. Reiterate that the work was completed as agreed and that the invoice remains due for payment.
• Suggest a partial payment: This is a crucial test of good faith. If a client has a genuine issue with one part of a project, they should have no problem paying for the parts they are happy with. Propose this clearly: "While we work to resolve the issue with [disputed item], please arrange for payment of the undisputed amount of £[X] from the invoice, which covers [undisputed items]." A client who refuses this is often revealing that their dispute is a delay tactic.

Escalating: Dealing with Deliberate Delays

If you've provided evidence, offered solutions, and the client is still refusing to pay or communicate constructively, you must assume they are acting in bad faith. It’s time to escalate your approach from collaborative problem-solving to formal credit control.

Your tone should shift from helpful to firm. You are no longer discussing the work; you are now enforcing a commercial debt.

Introduce Late Payment Legislation

For business-to-business (B2B) transactions in the UK, you have powerful legal rights under the Late Payment of Commercial Debts (Interest) Act 1998. If your contract doesn't specify a payment date, the law states payment is late 30 days after you deliver the goods/service or the day the customer receives the invoice (whichever is later).

You can inform your client that as the invoice is now significantly overdue and the dispute has been addressed, you are entitled to charge:

1. Statutory Interest: This is currently set at 8% plus the Bank of England base rate. You would explain that this interest is now accruing daily on the outstanding amount. As the base rate changes, you should always refer to the current rate on the Bank of England's website when calculating this.
2. Fixed Sum Compensation: You are also entitled to a one-off compensation payment to cover the cost of recovering the debt. The amount is set by law and depends on the size of the debt.

Debt Amount	Fixed Sum Compensation
Up to £999.99	£40
£1,000 to £9,999.99	£70
£10,000 or more	£100

Simply informing a reluctant client of these statutory charges, and your intention to add them to a revised invoice, can often be enough to prompt payment.

Send a Letter Before Action (LBA)

If this still doesn't work, the final step before legal proceedings is a Letter Before Action. This is a formal letter that sets out the debt, the history of the dispute, the evidence you've provided, and a final deadline for payment.

An LBA must clearly state:

• The total amount owed (including any statutory interest and compensation you have added).
• A summary of the original agreement.
• The steps you have taken to resolve the dispute.
• A final date by which payment must be made (e.g., 7 or 14 days).
• A clear statement that if payment is not received by this date, you will begin legal proceedings to recover the debt without further notice.

This is a serious legal document and often prompts payment from even the most difficult clients who wish to avoid court action.

Final Escalation Options

If the LBA is ignored, you have to decide if the amount owed is worth the time, cost, and stress of legal action. Your main options in the UK are:

• Mediation: A neutral third-party mediator helps you and the client reach a compromise. This is less adversarial than court but requires both parties to participate willingly.
• Money Claim Online (Small Claims Court): For debts up to £10,000 in England and Wales, this is a relatively low-cost and straightforward online process. You pay a fee based on the amount you're claiming, and if you win, you can usually claim these costs back from the debtor.
• Statutory Demand: For undisputed debts over £750 owed by a limited company, you can issue a Statutory Demand. This gives the company 21 days to pay. If they fail to pay and do not challenge the demand, you can then petition the court to have the company wound up (liquidated). It's an extremely powerful tool but should be used with caution and legal guidance, as it can be costly if the debt is genuinely disputed.

Prevention is Always Better Than Cure

Handling disputes is time-consuming. The best strategy is to minimise the chances of them happening in the first place.

• Watertight Contracts: Have a clear, written contract or scope of work for every project. It should detail exactly what you will deliver, what is excluded, payment terms, and the process for handling changes.
• Get Sign-Offs: For longer projects, build in milestones where the client formally signs off on stages of the work. This prevents them from complaining about something at the end that they approved weeks earlier.
• Invoice Accurately: Double-check every invoice before you send it. Ensure the PO number is correct, the amounts are right, and it's being sent to the correct person or accounts payable department.
• Communicate Proactively: Keep your client updated on progress. If you're going to be late, tell them in advance. A lack of communication is a breeding ground for mistrust and disputes.

---

Managing a disputed invoice requires a cool head and a clear process. By categorising the problem, communicating professionally, and knowing when to escalate, you can navigate these difficult situations, protect your business, and get the payment you're owed. While a robust chasing system can't prevent a bad-faith dispute, automating the simple follow-ups frees up your time to focus on resolving these more complex and demanding client issues when they arise.

InvoiceReminder helps UK small businesses, freelancers, and accountants automate their invoice chasing. It connects to Xero, Sage, QuickBooks, and FreeAgent to send scheduled reminders for overdue payments, so you can stop chasing by hand. The system provides a clear audit trail of communications, which is invaluable when a client claims an invoice was never received. The Free plan currently includes unlimited email reminders at no cost.

Frequently asked questions

What if a client just ignores my emails about their dispute?

If a client raises a dispute and then ignores your attempts to get specifics or resolve it, you should treat this as a deliberate delay tactic. After a reasonable number of attempts to engage (e.g., 2-3 emails over a week), you should move to the formal escalation process. Send a final email stating that as they have not provided details of their dispute, you consider the invoice valid and due, and will begin adding statutory interest if it is not paid by a set date.

Can I charge late payment interest on a disputed invoice?

This is a grey area. Legally, you can only charge interest on an overdue debt. If there is a genuine, substantive dispute over whether the money is owed at all (e.g., the work was genuinely not completed), then it is not yet a clear 'debt'. However, if the dispute is frivolous, a delay tactic, or relates to a tiny portion of the invoice, you can and should assert your right to charge interest on the overdue, undisputed amount. It's often best to state your intention to add interest once the dispute is resolved in your favour.

How much does it cost to use the small claims court?

The cost for making a claim via Money Claim Online in England and Wales depends on the size of the debt. Fees start from as little as £35 for claims up to £300 and increase on a sliding scale. For example, a claim for a debt between £1,000 and £1,500 currently costs £80. These fees can usually be added to the claim and recovered from the debtor if you win your case. This is general guidance, and you should always check the latest official government fees.

Should I use a debt collection agency for a disputed invoice?

Using a debt collection agency is an option, but it's often better for undisputed debts where the client is simply refusing to pay. For a genuinely disputed invoice, an agency has no more power than you do to resolve the underlying issue. They will typically send letters and make calls, which you have already done. Resolving the dispute first is more effective; if payment is still not made after the dispute is resolved, then a debt collector or legal action is the next logical step.

What's the difference between a credit note and a corrected invoice?

A credit note is a formal financial document that cancels out a previously issued invoice, either in full or in part. You issue it when a client is not required to pay the original amount (e.g., they returned goods, or you've agreed to a discount after a dispute). You would then issue a new invoice for the correct amount if a balance is still due. Simply editing and resending an old invoice can cause confusion and accounting problems. The correct process is: Credit Note to cancel the old invoice, then a new Invoice for the revised amount.

A client claims they never received the invoice, but my system shows they opened the email. What now?

This is strong evidence against their claim. Respond politely but firmly. You can say something like, "I've re-attached the invoice for your convenience. My email system indicates the original email with the invoice was delivered and opened on [Date] at [Time]. Perhaps it was overlooked internally? Please could you ensure this is processed for payment." This shows you have a robust process and evidence, without being overly accusatory. It puts the onus on them to explain the discrepancy.