Business · official-source review · reviewed 2026-10-10
Small businesses either waive late fees entirely or apply them inconsistently because they never calculate the number.
Compute a flat or percentage late fee and the new total due.
Freelancers and small business owners adding late fees to overdue invoices.
Use the source document or official route that applies to your situation. This guide does not contact another person or verify external information.
Only apply fees stated clearly in your signed contract or invoice terms.
Count calendar days past the due date.
Apply the percentage or flat fee stated in your terms.
Send a polite reminder with the updated total due.
A $1,200 invoice 15 days overdue at 1.5% per month carries a $9.00 late fee, for a new total of $1,209.
Use your own source and details. The example is not a record about a real person or organization.
U.S. Small Business Administration · reviewed 2026-10-10
What this source supports: Clear invoice terms, late fee policies stated upfront, and polite reminders reduce late payment.
Source limit: Late fee rules vary by jurisdiction; state your terms in your client agreement.
These sources support the statements above. They do not show that every person needs this guide. They do not show a specific result.
This App calculates a fee from the terms you define. It does not send an invoice or enforce payment.
Late fee rules vary by jurisdiction; state your terms in your client agreement.
Use current instructions from the responsible organization. This guide is a planning aid, not an official decision or a substitute for qualified advice.
Calculate a late fee from the invoice amount, rate, and days overdue.
This computes from your terms. It does not send invoices or provide legal advice.
You enter every number yourself. The sources support the method and the limits. They do not produce a result for your specific case. Keep the original documents next to the sheet you build.
The App computes the worked example with your own numbers, in your browser.
APP 1
Calculate a late fee from the invoice amount, rate, and days overdue.
Free · no account · no upload
Open Invoice Late Fee CalculatorThe App runs in this browser. It does not send or save entries. Copy, download, or print only when you choose.
This guide uses short, direct instructions as an ASD-STE100-style writing target. It is not a formal certification.
Companion App: Invoice Late Fee Calculator. It runs in this browser and does not upload your entries.
This guide is edited for clarity and checked against the sources it links. It is not a substitute for official instructions or qualified advice. A linked source does not show that every person needs this guide.