How do I calculate a late fee on an invoice?

Use a one-time percentage of the outstanding balance, a flat dollar amount, or a monthly percentage multiplied by the number of overdue months. Add that late fee to the original balance to get the new amount due.

What percentage should I charge as a late fee?

There is no single rate that applies everywhere. The permitted amount can depend on your contract and applicable law.

When can I charge a late fee?

It depends on the payment terms you agreed with the customer, any grace period you offered, and the rules that apply in your jurisdiction. A fee usually starts only after the due date and grace period have passed.

Can I charge a recurring monthly late fee?

Some agreements allow a recurring monthly fee on overdue balances. Charge one only if the customer agreed to it and the fee is permitted by applicable law.

Is a late fee the same as interest?

No. A late fee is usually a set charge—a flat amount or a percentage—added when an invoice is overdue. Late interest accrues over time on the unpaid balance, often as a daily or monthly rate.

Late Payment Fee Calculator

Calculate a late fee and updated balance for an overdue invoice.

Outstanding invoice amount

Invoice due date

Calculate through

Grace period (days)

Fee method

Late fee (%)

Late fee summary

New amount due: $2,100.00
Late fee: $100.00
Original balance: $2,000.00
Days subject to late fees: 14
Fee method: Percentage fee (5%)
Monthly periods: 0

Late-fee rules vary by contract and jurisdiction. Confirm that the fee you charge is permitted by your agreement and applicable law.

Create an invoice

Ready to send it? Open the Invoice Generator or browse all calculators.

How to calculate a late payment fee

Choose the method that matches your invoice terms, then add the late fee to the outstanding balance.

Percentage fee: $2,000 × 5% = $100 late fee. New amount due is $2,100.
Flat fee: $2,000 + $25 = $2,025 due.
Monthly fee: $2,000 × 1.5% × 3 months = $90 late fee. New amount due is $2,090. The monthly rate is applied once per period and is not compounded.

Late fees and late interest are not the same

A late fee is a set charge added after an invoice is overdue—either a flat amount or a percentage of the balance. Late interest keeps accruing on the unpaid amount over time. This calculator covers late fees only, not interest.

Frequently asked questions

How do I calculate a late fee on an invoice?: Use a one-time percentage of the outstanding balance, a flat dollar amount, or a monthly percentage multiplied by the number of overdue months. Add that late fee to the original balance to get the new amount due.
What percentage should I charge as a late fee?: There is no single rate that applies everywhere. The permitted amount can depend on your contract and applicable law.
When can I charge a late fee?: It depends on the payment terms you agreed with the customer, any grace period you offered, and the rules that apply in your jurisdiction. A fee usually starts only after the due date and grace period have passed.
Can I charge a recurring monthly late fee?: Some agreements allow a recurring monthly fee on overdue balances. Charge one only if the customer agreed to it and the fee is permitted by applicable law.
Is a late fee the same as interest?: No. A late fee is usually a set charge—a flat amount or a percentage—added when an invoice is overdue. Late interest accrues over time on the unpaid balance, often as a daily or monthly rate.

Put the fee on the invoice with the Invoice Generator. For policy wording and legal basics, see Invoice Late Fees and Invoice Payment Terms. When an invoice is already unpaid, follow How to Collect Unpaid Invoices or browse All Calculators.

Late Payment Fee Calculator

How to calculate a late payment fee

Late fees and late interest are not the same

Frequently asked questions

Related guides