1. The invoice itself
A clear, itemised invoice with the date, a description of what was supplied, the amount, your payment terms and the due date. This is the spine of the claim — everything else supports it.
Guide
What evidence
do you need?
You do not need a lever-arch file to recover an unpaid invoice — but a few well-kept documents make every stage faster and harder to argue with. Here is the checklist.
Direct answer
To claim an unpaid invoice you mainly need: the invoice, something showing what was agreed (a contract, purchase order, quote or email), proof you delivered, and a record of having chased payment. For an undisputed B2B debt up to £10,000 in England & Wales, that is usually enough.
TL;DR
- The invoice — itemised, with terms and a due date.
- Proof of what was agreed (contract / PO / quote / email).
- Proof you delivered the goods or service.
- The chase trail — shows the debt is undisputed.
- A clean figures breakdown (incl. interest, if claimed).
The checklist
Five things
worth keeping.
Gather what you can — gaps are normal and do not necessarily stop you. The aim is to show the debt is real and undisputed.
2. Your written terms or agreement
Whatever sets out what was agreed: a signed contract, a purchase order, an accepted quote, or even the email thread where the client agreed the work and the price. A formal contract is helpful but not essential — what matters is showing the debt is owed and undisputed.
3. Proof you delivered
Evidence the goods or service were provided: a delivery note or signed proof of delivery, timesheets, a completion sign-off, or the deliverable itself. This pre-empts the most common stalling tactic — that nothing was received.
4. The chase trail
Copies of the reminders you sent and any replies. A record that you asked for payment and the debtor did not dispute the debt is powerful: it shows the amount is undisputed and that you followed the Pre-Action Protocol before escalating.
5. The figures
A short statement of account and, if you are adding them, a breakdown of the statutory interest and fixed compensation claimed. Getting the numbers right and showing your working makes the claim easy to accept and hard to argue with.
One caveat worth stating plainly: this checklist is for an undisputed debt. If the customer genuinely disputes the goods or service, that is not a simple late payment and may need legal advice — it falls outside this workflow. When you are ready, see the full recovery process or how to issue a claim on MCOL.
FAQs
Common questions,
answered.
What evidence do I need to claim an unpaid invoice?
At minimum: the invoice, something showing what was agreed (a contract, purchase order, accepted quote or email), proof you delivered, and a record of having chased payment. For an undisputed B2B debt up to £10,000 in England & Wales, that is usually enough to send a Letter Before Action and, if needed, issue a claim.
Do I need a signed contract?
Not necessarily. A signed contract helps, but a purchase order, an accepted written quote, or an email exchange agreeing the work and price can establish the agreement. The key question is whether the debt is genuinely disputed — not whether one specific document exists.
What if I only have the invoice?
An invoice plus proof you delivered and a record that you chased payment is often enough for an undisputed debt. Gather what you can; gaps are common and do not necessarily stop you. RobinReturn is not a law firm and does not give legal advice.
How does this evidence get used?
It underpins each stage: the Letter Before Action references the invoice and amount, and if the claim proceeds to Money Claim Online your Particulars of Claim set out the debt and what supports it. Keeping it organised from the start makes every later step faster.
Got the basics?
Start the chase.
You do not need everything to begin with a reminder. RobinReturn is not a law firm and does not give legal advice.