Invoice Late Fee Calculator
Enter the invoice amount, the number of days late, and your fee terms. The calculator shows the late fee and the new total.
Your numbers stay in your browser. Nothing is sent to a server.
How the formulas work
Flat fee: the late fee is the flat amount you entered. The new total is the invoice amount plus the fee.
One-time percent: late fee = invoice amount x percent. A 5% fee on a $1,000 invoice is $1,000 x 5% = $50.00.
Percent per month: late fee = invoice amount x percent x days late / 30. A 1.5% monthly fee on a $1,000 invoice that is 45 days late is $1,000 x 1.5% x 45 / 30 = $22.50.
How to calculate a 1.5% monthly late fee
Multiply the invoice amount by 0.015, then multiply by the number of days late, then divide by 30.
On a $1,000 invoice that is 45 days late: $1,000 x 0.015 x 45 / 30 = $22.50. The new total is $1,022.50.
What is a reasonable late fee?
Your contract and your state's law decide what you can charge.
New York's banking regulator said in an informal letter of March 22, 2000 that "a customer must be given notice of the existence of a late charge" and that a late charge cannot be enforced without an agreement. Other states differ. Check the rules in your state before you set a rate.
How to charge a late fee
Put the fee in the invoice terms or the contract before the work starts, not afterward. After the due date passes, add the fee as its own line on the past-due notice or the next invoice, with the rate and the number of days.
Make the next invoice on your phone
Paid: Invoice & Estimate Maker makes invoices with a due date and line items for the fee, on iPhone and iPad. First 6 documents free (invoices and estimates together) with every feature, then $4.99 once. No subscription.
Free documents print a small footer: "Created with Paid · pokkle.com/invoice-maker". The purchase removes it.
Paid does not calculate late fees, track overdue invoices, or send reminders.