Invoice Late Payment Fee Calculator

"Calculate interest charges and penalties on overdue invoices in seconds."

Late payments can disrupt your cash flow and profitability. Use this calculator to find out exactly how much interest or late payment fee to charge based on the overdue duration, annual interest rate, and invoice value. Ideal for freelancers, agencies, and small business owners managing accounts receivable.

Invoice Details

Enter your invoice and payment information

Invoice Amount ($)

Invoice Due Date

Payment Date

Annual Interest Rate (%)

Flat Late Fee ($) (optional)

Compounding Type

Jurisdiction (Optional)

Enter your own rate

Late Payment Analysis

Detailed breakdown of late payment fees and interest

Days Late

31 days

Interest Accrued

$34.08

Flat Fee

$25.00

Total Late Fee

$59.08

Payment Summary

Fair Payment Terms Compliant

Original Invoice Amount:$5,000.00

Late Payment Fees:$59.08

Total Amount Payable:$5,059.08

Cost Comparison

How to Calculate Late Payment Interest

Understanding the formulas and legal requirements for late payment fees

Late Payment Interest Formula

Late payment interest is generally calculated as:

Late Fee = Invoice Amount × (Interest Rate / 100) × (Days Late / 365)

Some contracts also include a flat late fee per invoice.

Example Calculation

For an invoice of $5,000, 30 days late, at 8% annual interest:

→ Late Fee = 5,000 × (0.08 × 30 / 365) = $32.88
→ Total = $5,032.88 (or $5,057.88 if $25 flat fee applies)

Jurisdictional Requirements

Different regions have specific rules for late payment interest:

European Union

ECB rate + 8% minimum for B2B transactions

United Kingdom

Bank of England rate + 8% for commercial debts

United States

Varies by state, typically 8-18% annual rate