Late payments cost UK small businesses £23.4 billion a year. Most never claim the statutory interest they're legally entitled to.
Under the Late Payment of Commercial Debts Act 1998, you're owed 8% above the Bank of England base rate on any overdue business invoice — automatically, without needing to go to court.
Current rate: 13.25% (8% + 5.25% BoE base).
I built a calculator. Feed it your invoice list — client name, amount, due date — and it works out exactly what you're owed in statutory interest, flags everything by severity, and generates a full report.
Test run on 10 mock invoices:
→ 8 overdue
→ £28,415 outstanding
→ £1,847 in statutory interest owed
→ Oldest invoice: 145 days late
That £1,847 is legally claimable. Most people don't know it exists.
Built in Python. Report exports to HTML and the logic is 30 lines.
Interested in this project?
I'm always happy to talk through how it was built, the problems it solves, or how something similar could work for you.