A client has not paid your invoice: what to do

There is a point where more polite emails stop being the answer. This is what to do at each stage, and what you are actually entitled to once a payment is genuinely late.

Days 3 to 14: work the sequence

Send a reminder at three days, a firmer one at seven, and a final one at fourteen with a date attached. Most invoices settle here. The three templates are ready to copy.

Keep every message. A dated sequence you can point to is worth more later than any single strongly worded email.

Around day 14: pick up the phone

Three ignored emails means email is not reaching the person who can authorise payment. A two-minute call often reveals the actual problem: the invoice needs a purchase order number, it went to someone who has left, or it is sitting in an approval queue nobody has looked at.

Follow the call with a short email summarising what was agreed. That is not distrust — it puts the commitment somewhere you can both see it.

Day 30: stop working, and put it in writing

If you have ongoing work for the same client, pausing it is the point at which an unpaid invoice becomes their problem rather than only yours. Say it plainly and without drama: work is paused until the outstanding invoice is settled.

This is also the moment for a formal letter rather than another email — the same facts, but stated as a demand with a deadline.

What UK law entitles you to

For qualifying UK business-to-business commercial debts, statutory interest and fixed recovery costs may be available under the Late Payment of Commercial Debts legislation. Whether a particular debt qualifies depends on the contract and the parties, so treat these as what to check rather than what automatically applies. All three are on GOV.UK rather than taken on trust:

Payment is late after 30 days when no date was agreed — counted from when the customer received the invoice or the goods or services, whichever is later. Where terms are agreed, they must usually be within 30 days for public authorities and 60 days for business transactions.

Statutory interest may be charged at 8% plus the Bank of England base rate on qualifying UK business-to-business commercial debts. The base rate changes, so check the current figure before quoting a number at anyone.

A fixed sum for recovery costs may also be claimed on qualifying debts, on top of the debt itself: £40 for debts up to £999.99, £70 for £1,000 to £9,999.99, and £100 for £10,000 or more. It can be charged once per payment, and reasonable additional costs of recovery may also be claimed.

In practice, the right to charge interest is more useful as leverage than as income. Mentioning that statutory interest is accruing moves invoices that a fourth reminder would not.

Beyond that: small claims

For debts that stay unpaid, the small claims route exists and is designed to be used without a solicitor. It is slow and it usually ends the relationship, so it is worth being honest with yourself about whether the amount justifies it.

What actually prevents this

Nearly every invoice that reaches day sixty was one that nobody chased at day three. The single highest-value change is not a better letter — it is following up early, every time, without deciding each occasion whether it feels awkward.