Send reminders as a planned sequence rather than ad hoc chasing: a courteous prompt shortly before the due date, a clear reminder once the invoice is overdue, then a formal written notice referring back to your agreed terms. Keep every message factual and dated, and quote the invoice number and the amount outstanding.
Match the channel to the customer. Email gives you a written record, a phone call often resolves a genuine query faster than another email will, and a letter carries more weight at the formal stage. Whichever you use, follow up in writing so there is a trail if the debt is later disputed.
Stay professional throughout. Reminders that read as aggressive can damage a relationship you rely on for repeat work, and they rarely get you paid any sooner. If a customer raises a problem with the invoice, deal with it quickly — unresolved queries are one of the most common reasons an invoice sits unpaid, and chasing harder does nothing to fix them.
UK businesses have a statutory right to claim interest and fixed compensation on late commercial payments. The interest is set as a margin above the Bank of England base rate and the fixed sums are banded according to the size of the debt, and both move, so check gov.uk for the figures applying at the time you claim rather than working from a number you have seen before. Whether to invoke that right is a commercial judgement as much as a legal one.
If late payment is persistent and starting to affect your ability to pay suppliers, staff or HMRC, get advice early — your accountant first, and free, impartial help is available from Business Debtline for small businesses and sole traders. CWAF is a credit broker, not a debt collection agency and not an accountant. Where borrowing genuinely is the answer we can talk you through the options, but taking on finance to cover money you are owed adds a cost of its own and is not the right move in every case.