Chase a former client much as you'd chase a current one: a short, factual message about what's owed, a statement of the open invoices and an easy way to pay. A client leaving doesn't cancel what they owe for work you've already done, and a calm approach, with an instalment offer if they need it, is more likely to get you paid and leave the door open, with a law firm as the last step rather than the first.
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The short version
- A client leaving doesn't cancel invoices for work already done.
- Write to the finance team with the open invoices, a way to pay and nothing about the break-up.
- Separate disputed invoices from undisputed ones and talk through the disputed ones first.
- Offer instalments, and remember statutory interest applies to business clients.
- Hand over to a law firm only after reminders, a final notice and a plan offer go unanswered.
What you can still ask for once a client has gone
When a client moves to another agency or brings the work in house, the relationship ends but their invoices don't. Anything you've already invoiced is still owed, and so is work delivered up to the end date and anything your contract says is payable during a notice period.
Before you send anything, check the contract or proposal for what was agreed about notice, out-of-scope work and costs you paid on their behalf, such as ad spend or software licences. It's easier to ask calmly when you're sure of your ground.
Then sort what's open into two piles. Picture a client who leaves at the end of September with two invoices outstanding: the final month's retainer of £3,000, which nobody disputes, and £1,400 for extra design rounds the client says they never signed off. The retainer can be chased in the normal way. The design rounds need a conversation first, because reminders about an invoice the client disagrees with are unlikely to get it paid.
What to send once they've left
Your main contact may have made the decision to move on, or left the business altogether. The finance team is usually a better place to write to, since paying supplier invoices is their job either way. Copy your old contact if they're likely to help.
Keep the first message short and in the same tone you'd use with a client you're still working with. Include:
- each open invoice with its number, amount and due date, or a statement that lists them;
- a link or the details they need to pay;
- a line asking them to let you know if anything is holding the payment up.
Leave out the history of the account, how the handover went and anything about the new agency. If the client feels the message is about the break-up, they're more likely to argue than to pay. A former client can still refer you or come back when the new arrangement changes, so it's worth sending an email you'd be happy for them to forward.
If a reminder or two goes unanswered, a call to the finance team can turn up an invoice stuck with someone who's left or a missing purchase order number.
If the invoice still isn't paid
Some former clients will pay in full as soon as they're asked. Others will have budgeted for the new agency and not for your last invoice. Offering to split what's owed into two or three monthly payments gives them an easy way to say yes, and a plan they've agreed to is easier to keep on track than a vague promise to pay soon.
If the client is a business and your contract doesn't set its own interest rate, you can claim statutory interest on a late invoice at 8% above the Bank of England base rate, plus a fixed sum of £40, £70 or £100 depending on the size of the debt. Some businesses mention it and offer to waive it if the invoice is paid by a set date, which can move things along without a fight.
There's time if you need it. In England and Wales you generally have six years from the date payment was due to bring a claim for a contract debt, though older debts are usually harder to collect in practice.
A law firm is the final step, for when reminders, a final notice and an offer of instalments have all gone unanswered and the amount is worth pursuing. A solicitor will usually send a letter before action first, which is sometimes enough on its own, and only then start a claim if the money still doesn't arrive.
How to keep chasing after the account closes
With Adfin, chasing continues on open invoices after a client has stopped buying from you, so ending a retainer doesn't stop the reminders on what's still owed. You can move former clients onto their own collection agent with a softer sequence, and send a statement with a link that lets them pay several invoices in one payment, or set up an instalment plan.
If a former client still hasn't paid, Escalations can take the invoice as far as a law firm. The last step is yours to pick: take the invoice back, or pass it to Garfield.Law, an SRA-regulated law firm that works with Adfin, which sends a letter before action and can then issue a claim in your business's name. Before that, the invoice goes through whichever steps you've chosen, such as a notice from a more senior colleague's mailbox, an offer to pay in instalments, an AI phone call and a final notice. If the client pays part of what's owed, the escalation stops.
Escalations are one of the enhanced skills on Adfin's collection agents, charged at 0.3% of an invoice only when an enhanced skill was used on it and that invoice is paid. On a £3,000 invoice that's £9.
Common questions
Can I still chase a client after they've ended our contract? Yes. Ending the contract stops future work, but invoices for work already done, and anything the contract says is due on notice, are still owed.
How long do I have to recover an unpaid invoice from a former client? In England and Wales, generally six years from the date payment was due for a contract debt. Scotland has different rules, so take advice on anything that old.
Can I add interest to a former client's overdue invoice? Yes, for a business client whose contract doesn't set its own rate. You can add interest at the Bank of England base rate plus 8%, and a fixed £40 to £100 for recovery costs, depending on the debt.
Should I offer a former client a payment plan? It's often worth offering if they can't pay in one go. Agree the amounts and dates in writing, and keep the plan short.
What should I do if a former client disputes the invoice? Stop chasing that invoice while you talk it through, and keep chasing anything that isn't in dispute. Have the contract and any sign-offs to hand.
When should I hand an unpaid invoice to a law firm? Once your reminders, a final notice and an instalment offer have gone unanswered, and the amount justifies the cost of a letter before action and a possible claim.
Sources
- GOV.UK - Late commercial payments: charging interest and debt recovery (accurate as of November 2026) https://www.gov.uk/late-commercial-payments-interest-debt-recovery/charging-interest-commercial-debt
- GOV.UK - Late commercial payments: claim debt recovery costs (accurate as of November 2026) https://www.gov.uk/late-commercial-payments-interest-debt-recovery/claim-debt-recovery-costs
- legislation.gov.uk - Limitation Act 1980, section 5 (accurate as of November 2026) https://www.legislation.gov.uk/ukpga/1980/58/section/5
- Adfin - Credit control (accurate as of November 2026) https://www.adfin.com/credit-control
