When the same clients sit in the over 90 days column month after month, it's usually because of how they pay, not a one-off slip: an accounts payable process your invoices don't fit, a dispute nobody has raised, a cash problem, or a low place in their payment queue. Find out which applies to each client, change the terms on the next piece of work, and give every very overdue invoice a set route to escalation.
In this article
The short version
- Compare three months of aged debtor reports to find the clients always over 90 days.
- The usual causes are an accounts payable process, an unraised dispute, cash trouble or low priority.
- Fix process and disputes with the accounts team; be firmer with cash trouble and low priority.
- Change terms on new work: deposits, milestones, direct debit retainers, or no new work until the balance is cleared.
- Escalations can end with a handover to Garfield.Law, which prices a letter before action at £7.50 plus VAT.
How to spot the clients who are always there
Your aged debtor report is a snapshot, so one month on its own won't show you a pattern. Put the last three months side by side and list the clients with a balance over 90 days in each. For most agencies and consultancies it's a short list, and often the same few names account for most of the oldest debt.
For each name, note three things: how much is over 90 days, whether newer invoices are being paid while older ones stay open, and whether the balance is growing or holding steady. A client who pays this month's invoice but never last spring's is telling you something different from one who has stopped paying anything.
Adfin's aged debtors view shows what each client owes broken down by age, and you can give each debtor an owner and a next step, so the same names don't roll over from one month to the next without anyone picking them up.
Four reasons a client stays over 90 days
| Reason | What you tend to see | What to try |
|---|---|---|
| Their accounts payable process | Invoices rejected or held for a missing purchase order, wrong entity or supplier form | Get the PO and supplier details right, learn their payment run dates and invoice to match |
| An unresolved dispute | Newer invoices paid, one older invoice left open, often after a scope change | Ask directly what's holding it, agree the figure or issue a credit note |
| Cash trouble | Part payments, slower replies, a balance that keeps growing | Talk early, agree an instalment plan in writing, take payment before further work |
| Low priority | Paid eventually, always late, no queries raised | Change the payment method, add statutory interest, raise it with someone senior |
You can usually fix the first two without any change to the relationship. Large clients often pay only on set dates, and an invoice that misses the cut-off or lacks a purchase order waits for the next run, then the one after. A call to the accounts team, not the person who commissioned the work, tends to find out what they need.
The last two need you to be firmer. With a client in cash trouble, the aim is to get paid while they still can. With a client who simply pays you last, the aim is to make paying late cost them more effort than paying on time.
New terms for the next project
You can't usually rewrite the terms on work already invoiced, but you can set different ones before the next piece starts. For a client who has sat over 90 days for months, any of these is reasonable to ask for:
- a deposit before work starts, or payment upfront for smaller jobs
- milestone invoices, so you're never carrying the full value of a project
- a monthly retainer collected by direct debit on a date you set
- a rule that new work starts once the overdue balance is cleared
Statutory late payment interest applies to business invoices whether or not your contract mentions it, at 8% above the Bank of England base rate, plus fixed compensation of £40, £70 or £100 per invoice depending on its size. For debts falling overdue between 1 July and 31 December 2026, the interest rate is 11.75% a year. Adding it consistently tends to move a low-priority client up the queue, and you can still choose to waive it.
When to escalate and when to let a client go
A client who stays over 90 days after a call, a statement and a change of terms needs a set route, so the invoice doesn't just get older. Adfin's collection agents can run escalations for you, as part of Enhanced credit control: a firmer notice sent from a more senior person's mailbox, an offer to pay in instalments, an AI phone call that says it's an AI, a final notice, then a handover. You choose the stages and the gaps between them, and any payment, including a part payment, stops the sequence.
At the handover, the invoice comes back to you or goes to Garfield.Law, Adfin's partner law firm, which is regulated by the Solicitors Regulation Authority. Garfield sends a letter before action, which it prices at £7.50 plus VAT, and if there's no response it can file a small claim of up to £10,000 in the county court in England and Wales. You stay the claimant throughout.
Letting a client go is a commercial call. Clients worth keeping tend to pay in the end once you've fixed the cause. A client whose balance keeps growing, who disputes every invoice after the work is delivered or who only pays when legal action is mentioned may be costing you more in time and cash than the work brings in.
Related guides
- How to read an aged debtor report
- What do your aged debtors tell you about your customers?
- What to do when a customer ignores your payment reminders: a staged approach for UK businesses
- What's the most cost-effective way to take an unpaid invoice to legal action?
- How to recover overdue invoices: the complete UK guide
Common questions
Why do some clients always pay late? Usually it's their process, an unraised dispute, a cash problem or a low priority for your invoices. Each one calls for a different response, so it's worth finding out which applies.
How do I find my chronic late payers? Compare your aged debtor report over three months and list the clients with a balance over 90 days each time. Note whether their balance is growing.
Should I stop working for a client who's always over 90 days? Not necessarily. Try changing the terms on new work first, such as a deposit or direct debit, and keep stopping work in reserve for clients whose balance keeps growing.
Can I charge interest on invoices over 90 days old? Yes, if the client is a business. Statutory interest runs at 8% above the Bank of England base rate, plus fixed compensation of £40, £70 or £100 per invoice.
How much does a letter before action cost? You can write one yourself. Garfield.Law, an online law firm, prices a letter before action at £7.50 plus VAT, with court fees separate if a claim follows.
How long should I give a business client to reply to a letter before claim? Usually 14 days in a straightforward case. For an individual or sole trader, the Pre-Action Protocol for Debt Claims gives them 30 days.
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
- Ministry of Justice - Practice Direction: Pre-Action Conduct and Protocols (accurate as of November 2026) https://www.justice.gov.uk/courts/procedure-rules/civil/rules/pd_pre-action_conduct
- Garfield.Law - Pricing chart (accurate as of November 2026) https://www.garfield.law/pricing-chart
- Adfin Help Centre - Escalations: what happens when a customer ignores your reminders (accurate as of November 2026) https://support.adfin.com/en/articles/17612506-escalations-what-happens-when-a-customer-ignores-your-reminders
