Free calculator · no account needed

Invoice late fee and due date calculator

Enter the issue date and payment terms to get the due date, then see how many days late the invoice is and what the late fee comes to.

Invoice amount ($)

Issue date

Payment terms

Count days late as of

Leave as today, or pick the date the client paid.

Late fee type

% per monthYearly interestFlat fee

Late fee per month (%)

Charged on the unpaid amount for each started 30 days, not compounded.

Late fee after 45 days

$75.00

Due date: Sep 2, 2026
Days late: 45
Amount due with fee: $2,575.00

Late fees and interest are only enforceable if your contract or invoice terms set them, and many US states cap them. Check your state's limit before charging. Not legal advice.

IN SHORT

An invoice's due date is the issue date plus the payment terms: net 30 from March 1 is March 31. A late fee only applies if your contract or invoice terms set one. Common clauses are a flat fee or 1 to 1.5 percent per month on the unpaid balance. Many US states cap late fees and interest, so check your state's limit before charging.

Prices and limits as of October 26, 2026.

Questions

What does net 30 mean?

The client has 30 calendar days from the invoice date to pay. Net 15, 45 and 60 work the same way. "Due on receipt" means the invoice is due the day it's sent.

Can I charge a late fee on an invoice?

Usually only if the client agreed to it beforehand, in your contract or in the terms on the quote and invoice. Adding a fee after the fact is hard to enforce.

How much can I charge as a late fee?

It depends on the state. Many states limit interest rates under usury laws, and limits differ for business clients and consumers. This calculator doesn't check state limits, so confirm yours before you set a rate.

How is 1.5% per month calculated here?

1.5% of the unpaid amount for each started 30-day period after the due date, without compounding. 45 days late on $2,000 is two periods: $60.

Related calculators

Know which invoices are late without a spreadsheet

SoloWOS Invoicing shows each invoice as sent, viewed, paid or overdue, and clients pay by card from the link. 14 days free, no card needed · Then Basic for $2/month.

Start your free trial See Invoicing