Freelance calculators
Invoice Late-Fee Calculator
Prorate a monthly or annual late-fee rate over the number of days overdue. Your inputs stay in this browser.
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What this calculator measures
This tool prorates a stated monthly or annual simple rate across overdue days. It does not decide whether a fee is legally enforceable.
Formula
Monthly Fee = Invoice x Rate x (Days / 30); Annual Fee = Invoice x Rate x (Days / 365)
Worked example
- 1A $2,000 invoice is 45 days late at 2% monthly.
- 2$2,000 x 0.02 x 45/30 = $60.
How to interpret the result
Charge only terms agreed in the original contract and permitted by governing law; statutory schemes may use different formulas.
Common mistakes and limits
- Adding a fee after signing, confusing annual and monthly rates, or compounding when the agreement specifies simple interest.
Frequently asked questions
Can I charge any rate?
No. Contract terms and local law may limit or prohibit fees.
Does this compound?
No. It prorates simple interest.
When does lateness begin?
Use the contractual due date or the date defined by applicable law.