Invoice Late Fee Calculator
Estimate a simple late fee from an overdue invoice balance. Use only a rate and fee allowed by your signed terms and applicable requirements.
Formula: Simple interest = overdue balance x annual rate x days late / 365. Total late fee = simple interest + permitted flat fee.
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Enter the numbers
Calculated result
Calculated late fee
$24.66
$24.66 simple interest plus $0.00 flat fee
Updated balance
$2,524.66
Original overdue balance plus the calculated fee
Daily interest amount
$0.82
Simple daily amount at the entered annual rate
Formula: Simple interest = overdue balance x annual rate x days late / 365. Total late fee = simple interest + permitted flat fee.
Use the result correctly
What the calculation means
A calculator does not make a late fee enforceable. The charge should match the signed agreement, invoice terms, and applicable limits. Do not add a fee retroactively when the customer never agreed to it.
Useful for
- Estimate simple interest for a past-due invoice
- Separate a permitted flat fee from percentage-based interest
- Show the customer how the updated balance was calculated
Frequently asked questions
Can I charge any late fee I want?
No. The fee should be agreed in advance and comply with applicable limits and rules. Verify your terms before charging it.
Does this calculator compound interest?
No. It calculates simple interest on the original overdue balance for the entered number of days.
Should tax be added to a late fee?
Tax treatment can vary. This calculator does not add tax; verify the treatment that applies to your transaction.
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