US reader note. This page uses US English but discusses UK tax, VAT, CIS, or payment rules. Treat it as UK-focused educational content, not US legal, tax, or accounting advice. US requirements vary by federal, state, and local rules, so check with a qualified professional before applying anything to a US business.

The late payment problem

Late payment is one of the biggest cash flow headaches for contractors in the UK. You have done the work, sent the invoice, and now you are waiting. Days turn into weeks. You do not want to be aggressive because you value the relationship, but you also need to pay your own bills. It is a balancing act that every sole trader and small business owner faces.

The good news is that there is a structured way to follow up on unpaid invoices in the UK that protects your cash flow without burning bridges. The key is escalating gradually -- starting soft, getting firmer, and only involving formal processes when everything else has failed.

Why invoices go unpaid

Before you assume the worst, it helps to understand the common reasons invoices go unpaid. Knowing the cause changes how you respond.

  • They forgot. Life gets busy. Your invoice arrived during a hectic week and slipped to the bottom of the pile. This is the most common reason by far.
  • The invoice went to spam. Email filters are aggressive. If you sent the invoice by email, it may never have reached the customer's inbox.
  • They are waiting on their own money. Landlords, property managers, and small businesses sometimes delay paying you because their own clients have not paid them yet.
  • There is a dispute about the work. The customer may be unhappy with something but has not told you. They are holding back payment as leverage rather than raising the issue directly.
  • Cash flow problems. The customer genuinely does not have the money right now. This does not mean they will never pay, but you need to know so you can agree a plan.
  • They are avoiding payment deliberately. This is rarer than people think, but it does happen. Some customers have no intention of paying and hope you will give up.

Your follow-up process should assume good faith at the start and get progressively more formal. That way, the customers who simply forgot will pay quickly, and the ones who are genuinely difficult will know you mean business.

A timeline for chasing: day by day

Here is a structured timeline that works for most UK contractors. Adjust the wording to match your style, but stick to the escalation pattern.

Day 1 -- the invoice due date

The day the invoice falls due is not the day to start chasing -- it is the day to make sure your paperwork is in order. Confirm that the invoice was delivered, that the payment details are correct, and that the customer knows the due date. If you use email, check your sent folder. If you use WhatsApp, check the read receipts.

If the payment has not arrived by end of day, there is no need to act yet. Give it a day or two. Bank transfers can take time, and some people pay at the end of the business day.

Day 7 -- a polite nudge

One week overdue. This is your first follow-up, and the tone should be light and friendly. The goal is simply to bring the invoice back to the top of their mind.

Keep it brief. Something along the lines of: you are just checking in, you wanted to make sure they received the invoice, and you are happy to resend it or answer any questions. Reference the invoice number and the amount so they can find it quickly. Do not mention penalties, interest, or consequences at this stage.

Most late payments get resolved at this point. A friendly reminder is often all it takes.

Day 14 -- a firmer follow-up

Two weeks overdue. The tone shifts slightly. You are still polite, but you are making it clear that the payment is overdue and you need it sorted.

Your message might say something like: you are following up on the invoice that was due on a specific date, the balance is still outstanding, and you would appreciate payment at the earliest opportunity. If there is a problem, ask them to get in touch so you can discuss it. Offering to talk shows good faith while also putting the ball firmly in their court.

Day 28 -- a formal overdue notice

Four weeks overdue. This is where you move from informal reminders to a formal overdue notice. The tone is professional and direct. No pleasantries, no apologies for chasing.

Your notice should clearly state the invoice number, the original due date, the total amount outstanding, and that the payment is now significantly overdue. Mention that you would like to resolve this without further action, but make it clear that if payment is not received within a set number of days, you will need to consider your options. You do not need to spell out what those options are yet -- the implication is enough.

Day 30 and beyond -- formal escalation

If you have followed up at 7, 14, and 28 days and still have no payment and no communication, it is time to escalate. You have been more than reasonable, and the customer has had every opportunity to pay or explain.

At this point, your options depend on the contract and jurisdiction. You may send a formal demand letter, discuss a payment plan, use a collections process, or consider small claims court. UK statutory-interest details later in this article are UK-specific.

UK note: the Late Payment of Commercial Debts Act

If you are a sole trader or limited company and your customer is a business (not a private individual paying for personal work), the Late Payment of Commercial Debts (Interest) Act 1998 gives you the right to charge interest and claim compensation on overdue invoices.

The statutory interest rate is 8% per year above the Bank of England base rate. Interest accrues daily from the day after the payment was due. You do not need to have agreed this in your terms beforehand -- it is a statutory right for business-to-business transactions.

On top of interest, you can also claim fixed compensation based on the size of the debt:

  • Debts up to 999.99 pounds -- 40 pounds compensation.
  • Debts from 1,000 to 9,999.99 pounds -- 70 pounds compensation.
  • Debts of 10,000 pounds or more -- 100 pounds compensation.

You can also claim reasonable costs of recovering the debt, such as the cost of sending recorded delivery letters or court fees.

Consumer vs business. The Late Payment Act applies to business-to-business transactions. If your customer is a private homeowner paying for personal work (not acting as a business), this specific legislation does not apply. You can still claim interest through the courts, but the automatic statutory rights described above are for commercial debts only.

You can use our free late payment calculator to work out exactly how much interest and compensation you are owed on any overdue invoice.

Letter before action: what it is and when to send one

A letter before action (sometimes called a letter before claim) is a formal written notice that gives the debtor one final chance to pay before you start court proceedings. It is not a legal requirement, but courts expect you to have sent one before making a claim. If you skip this step and go straight to court, the judge may hold it against you, even if you win.

Your letter before action should include:

  • A clear statement that this is a letter before action.
  • The total amount owed, broken down by invoice amount, any statutory interest, and compensation.
  • A summary of your previous attempts to collect payment, including dates.
  • A deadline for payment -- 14 days is standard.
  • A statement that if the debt is not paid within the deadline, you intend to issue court proceedings without further notice.

Send the letter by recorded delivery so you have proof it was received. Keep a copy for your records. Many debtors pay at this stage because they realize you are serious and the costs will only go up if they ignore it.

UK note: small claims court and Money Claims Online

If the letter before action does not produce payment, the next step for debts under 10,000 pounds in England and Wales is the small claims track of the county court. The easiest way to file a claim is through Money Claims Online (MCOL), the government's online claims service.

Here is how the process works:

  1. File your claim online. You enter the amount owed, the details of the debt, and the defendant's name and address. You pay a court fee which varies based on the claim amount -- for example, roughly 35 pounds for a claim up to 300 pounds, and up to 455 pounds for claims approaching 10,000 pounds.
  2. The court sends the claim to the debtor. They have 14 days to respond. They can pay in full, acknowledge the claim and ask for more time, file a defense, or do nothing.
  3. If they do not respond. You can request a default judgment, which means the court orders them to pay without a hearing.
  4. If they file a defense. The case goes to a hearing. For small claims, this is usually informal. You do not need a lawyer, and costs are kept low.
  5. Enforcement. If the debtor still does not pay after judgment, you can apply for enforcement -- such as a warrant of control (bailiffs) or an attachment of earnings order.

The small claims process is designed for exactly this kind of situation: straightforward debts where the amount is not in question. The fees are recoverable from the debtor if you win, and you do not need legal representation.

Important. This article is general information, not legal advice. For specific situations involving disputed invoices, contracts, or debt recovery, speak to a lawyer or contact Citizens Advice.

Getting the tone right: polite vs firm

One of the hardest parts of chasing payment is knowing how to phrase things. Too soft and you get ignored. Too aggressive and you damage the relationship -- or worse, provoke a dispute.

In the early stages (day 7), your message should sound like you are doing the customer a favour by reminding them. You are being helpful, not demanding. Think of it as a courtesy notification -- the sort of thing anyone would appreciate if they had genuinely forgotten.

By day 14, your tone should make it clear that you are aware the payment is late and that you expect it to be resolved. You are not angry, but you are not going to pretend everything is fine. You are giving them the benefit of the doubt while drawing a line.

By day 28, the language shifts to formal. You are not asking them to pay at their convenience -- you are telling them the payment is overdue and that further action will follow if it is not received. Short sentences. Clear deadlines. No ambiguity.

If it reaches the letter before action stage, the language is purely factual. Dates, amounts, deadlines. No emotion, no persuasion. You are creating a paper trail that a court can review.

How WOPA automates payment reminders

Following up manually at 7, 14, and 28 days takes discipline. When you are on a roof, under a sink, or knee-deep in a rewire, remembering to chase an invoice from three weeks ago is the last thing on your mind. This is exactly the kind of task that should be automated.

WOPA handles the entire reminder sequence for you. When you create an invoice through WhatsApp, WOPA emails the PDF to your customer and then monitors whether the invoice has been paid. If it has not, WOPA automatically sends polite reminders at 7 days, firmer follow-ups at 14 days, and formal overdue notices at 28 days.

You do not need to set anything up, remember any dates, or write any follow-up messages. When your customer pays, you tell WOPA and the reminders stop immediately. If a customer replies to a reminder with a question or dispute, you are notified through WhatsApp so you can handle it personally.

The reminders are professional and correctly timed, which means your customers are more likely to pay on time and less likely to feel harassed. You get paid faster without the awkwardness of writing those messages yourself.

Join the waitlist to get US beta access when WOPA launches.