Business Calculators

Invoice Late Fee & Interest Calculator

Work out exactly what an overdue invoice owes you — by your own contract rate, a plain annual rate, or the UK's statutory late-payment formula for reference.

Inputs

Invoice

Invoice amount

Due date

Calculate as of

Interest terms

Method

Monthly late-payment rate

%/mo

Enter the rate your invoice or contract actually states — there's no universal default, so this starts at 0. The invoice/contract also states the equivalent yearly rate

Annual interest rate

%/yr

Simple interest, prorated by days late ÷ 365.

Current Bank of England base rate

Statutory rate = base rate + 8% (Late Payment of Commercial Debts (Interest) Act 1998). Look up the current base rate — it changes. Shown in GBP.

Amount owed

Fill the form and press Calculate.

Canada's Interest Act disclosure rule

Section 4 of the federal Interest Act says that when a contract states an interest rate for a period shorter than a year — per month, per week — and does not also state the equivalent yearly rate, no more than 5% per year can actually be charged or recovered, no matter what the monthly figure works out to. A monthly late-fee clause that never spells out its annual equivalent is capped at 5%/year by law. Leave the checkbox above unticked to see both figures.

UK statutory rate, for reference

The UK's Late Payment of Commercial Debts (Interest) Act 1998 sets business-to-business statutory interest at the Bank of England base rate plus 8%, and adds fixed compensation on top: £40 under £1,000, £70 from £1,000–£9,999.99, and £100 at £10,000 or more. It's not the law in Canada, but it's a real, commonly cited benchmark for what a "serious" late-payment rate looks like.

Disclaimer

This calculator provides estimates for educational and informational purposes only, based on simple (non-compounding) interest. It is not legal or accounting advice. Enforceability of a late-fee clause depends on what your contract or invoice actually says and the law that applies to it. Confirm your own terms and, for anything contested, talk to a lawyer or accountant.