Find out exactly how much statutory interest and compensation you're legally owed under the Late Payment of Commercial Debts Act 1998.
Under the Late Payment of Commercial Debts (Interest) Act 1998, UK businesses have the legal right to charge statutory interest on overdue invoices at 8% above the Bank of England base rate, calculated daily from the date payment became due.
You're also entitled to a fixed compensation amount on top of interest, set by law: £40 for debts under £1,000, £70 for debts between £1,000 and £9,999, and £100 for debts of £10,000 or more.
This applies automatically — you don't need to have mentioned it on your original invoice for the right to exist, though mentioning it in your payment terms makes it easier to enforce.