Invoice late fee calculator
Late fees only work if they were agreed before the work started and the rate is enforceable where you are. This shows what you are owed, and what your rate looks like annualised.
Total now owed
Not enough detail yet
Enter the invoice amount and how overdue it is to work out what you are owed.
- Original invoice
- —
- Late fee
- —
- Months overdue
- —
- Annualised rate
- —
Nothing you type leaves your browser.
Common questions
What is a reasonable late fee for an invoice?
1 to 1.5% per month is the common range, which annualises to 12 to 18%. Several states cap what you may charge, and an unenforceable rate is worse than a modest one.
Can I add a late fee after sending the invoice?
Rarely with any force. A late fee generally has to be in the contract or on the original invoice before the work started. Adding one afterwards is hard to enforce.
Should late fees compound?
Simple interest is the safer default. Compounding fees are harder to defend and, in some states, unenforceable.
What people use next
Estimates based on published federal rules for tax year 2026. State and local tax is not included. This is general information, not advice about your situation.