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Invoice Late Fee Calculator — Calculate What You’re Owed for Late Payment

This late payment fee calculator works out fixed, percentage, or statutory calculations and gives copy-ready invoice wording.

Invoice late fee calculator

LATE FEE CALCULATION

Original invoice: $0.00

Late fee applied: $40.00

New total due: $40.00

📋 INVOICE WORDING (copy-paste ready)

A late payment fee of USD40.00 has been applied to this invoice, which was due 0 days ago. New total due: USD40.00.

Add fee terms once, then automate reminders so clients act before extra charges stack up.

Start free

How to calculate a late fee on an invoice

Fixed fee is simple and predictable. Monthly percentage scales better for larger invoices. UK statutory interest can be legally enforceable for B2B invoices under the Late Payment Act.

What late fee rate is standard

  • US: no federal statutory rate; 1–2% monthly is common (state law applies).
  • UK: Bank of England base rate + 8% statutory for qualifying B2B debts.
  • EU: Late Payment Directive sets 8% above ECB reference for B2B.
  • Australia: penalty interest often defined by state-level frameworks.

Does charging a late fee damage client relationships?

It can if it is a surprise. If agreed up front in clear payment terms, it is usually treated as professional policy rather than personal conflict.

Set terms first with the Payment Terms Generator, then estimate exposure in the Late Payment Cost Calculator.

External references

Written by Pasko Djonovic, Founder at ChaseAI • Last updated May 6, 2026

FAQ

In the UK, statutory B2B interest can apply automatically. In many US states, contractual terms are generally required.

Apply fair fees with confidence

Pasko Djonovic, Founder at ChaseAI

Written by Pasko Djonovic, Founder at ChaseAI • Last updated April 29, 2026