Documenting a UK commercial contract dispute over withheld milestone payments

If a client or counterparty has withheld a milestone payment, your priority is to create a clear, time-stamped record that shows (a) what was due, (b) why you say it is owed, and (c) what attempts you made to resolve the issue before court. For England & Wales that record supports the Letter of Claim expected by the Civil Procedure Rules' pre-action guidance and is reusable if you later issue a Money Claim Online or Part 7 claim. See the Civil Procedure Rules' Pre-Action Protocols for the formal expectations around pre-action conduct and debt claims (Pre-Action Protocols – Civil Procedure Rules).

Create a tight, chronological bundle and a short narrative (one or two pages) that a solicitor or a district judge can read quickly. Below I explain what to gather, how to assemble it, how to write a Letter of Claim that meets pre-action expectations, limitation risk to watch, and what comes next if the other side disputes the facts.

What documents and evidence actually matter

Collect the documents that directly prove the contract, the milestone, performance and the non-payment. Focus on primary records rather than impressions.

• The contract and any written variations or change orders that alter the milestone, price, or acceptance criteria. If milestones are defined in a statement of work, include that.
• The milestone schedule or delivery plan showing the due date and acceptance conditions.
• Invoices and payment notices tied to the milestone, with invoice numbers and issue dates.
• Proof of delivery or completion: acceptance emails, sign-offs, delivery receipts, test reports, timesheets, or demo records showing the work met the milestone criteria.
• All correspondence about the withheld payment: emails, messages, internal notes summarising phone calls, and any formal notices. Preserve originals and create PDFs.
• Records of any set-off or defect complaints from the payer (so you can address their stated reasons for withholding).
• Financial records showing the unpaid amount remained outstanding: chased invoices, reminders, any partial payments and dates.
• A short witness statement or contemporaneous note from the project lead summarising key events and dates.

Put these in chronological order and produce a one-page index that maps each item to the timeline and to specific paragraphs of your draft Letter of Claim or particulars of claim.

How to draft a Letter of Claim that fits pre‑action expectations

The Pre-Action Protocols and the Practice Direction on Pre-Action Conduct expect a Letter of Claim that concisely sets out the dispute, the amount claimed, relevant documents, and a reasonable time to respond. The Debt Pre-Action Protocol is the closest practical model for withheld milestone payments where money is owed. Use plain language and attach the evidence bundle index.

A useful Letter of Claim structure (short):

1. Who you are and the contract reference.
2. What milestone fell due, the amount unpaid, and the invoice(s) or payment notice reference.
3. Brief statement of performance (e.g., "Deliverables A–C completed and accepted on [date], see acceptance emails at bundle items 4–6").
4. Why the payer’s stated reason—if given—for withholding is incorrect or insufficient (cite the documents briefly).
5. The precise sum claimed, any contractual or statutory interest you propose to claim, and a breakdown of principal and interest.
6. A clear deadline for response (a reasonable period is often 14–30 days depending on complexity) and the consequence of no response (possible court proceedings). Do not state unrealistic or legally binding deadlines beyond what the CPR requires.
7. Invitation to discuss settlement and suggested next steps (meeting, mediation, or payment plan).
8. List of documents enclosed and how you delivered the letter (email with delivery/read receipt and/or recorded post).

Keep the Letter of Claim focused: a short narrative plus the index and attachments. The court and a costs judge will expect evidence you attempted to resolve the dispute before issuing. The Civil Procedure Rules’ list of Pre-Action Protocols explains these expectations (Pre-Action Protocols – Civil Procedure Rules).

Practical example (illustrative)

Imagine you supplied software modules A–D with milestones at 25% intervals. Milestone 3 for module C was certified complete on 20 March; invoice 003 for £24,000 was issued 25 March and remained unpaid. The payer emailed on 2 April alleging performance issues but did not specify defects. Your documentation should include the certification email, demo logs, invoice 003, the payer's email, your detailed response addressing the alleged defects, and chase emails. Your Letter of Claim would say: "Milestone 3 completed and accepted on 20 March; invoice 003 unpaid; the alleged defects were raised on 2 April without particulars; full response provided on 5 April; please pay £24,000 by [date]."

If the payer provides particularised defects, record their specifics and evidence of remedial offers; courts weigh whether withholding was a genuine dispute or an improper non‑payment.

Time limits, interest and court options

Most commercial contract claims in England & Wales are governed by the six‑year limitation for actions on simple contract (Limitation Act 1980, s.5). That period normally starts when payment became due and was not made; if the date is close, prioritise formal steps quickly (Limitation Act 1980).

If you decide to issue a claim, small or straightforward money claims can be started using Money Claim Online (MCOL) for fixed sums; the GOV.UK MCOL user guide explains how to begin and what to include (Money Claim Online (MCOL) user guide). For larger or more complex disputes, a Part 7 claim in the county court or High Court may be appropriate under the Civil Procedure Rules (Rules & Practice Directions – Civil Procedure Rules).

State any contractual interest clause and/or statutory interest you intend to claim in your Letter of Claim and later in the claim form; be prepared to justify the rates and the calculation.

What if the other side disputes the amount or facts? How to adjust your record

When the payer disputes quality or scope, add two things to your bundle: (1) the payer's specific allegations, and (2) your direct evidence that answers each allegation (test results, acceptance records, witness notes). Keep your narrative neutral and evidence-focused — a judge is more persuaded by aligned, dated documents than heated language.

If disputes are genuinely technical, consider whether the contract requires adjudication, expert determination, or arbitration before court — those clauses override normal court pre-action choices and may be mandatory.

Next practical steps and a sensible timeline

• Immediately assemble the evidence bundle and index (1–3 days).
• Send a clear Letter of Claim with the bundle index attached; allow 14–30 days for reply depending on complexity.
• If no satisfactory response, consider MCOL for simple sums or a Part 7 claim for larger/complex matters; take legal advice if the limitation clock is running or the contract requires alternative dispute resolution.

A professionally drafted demand letter can improve your chances of payment and of recovering costs later. If you want professional help preparing a structured demand from the information you hold, consider a document preparation service that works from your materials rather than legal representation. One such option is , which prepares documents from customer-supplied information; customers remain responsible for decisions about sending documents.

Be mindful: this guidance focuses on England & Wales practice under the Civil Procedure Rules and related guidance; Scotland and Northern Ireland use different procedures and limitation rules.

For help preparing a professional demand letter, BeforeSuit can help you prepare your next steps.