Invoice generatorFree, no sign-up — your invoice is saved in your browser, not in an account

Late payment fee calculator

Work out what an overdue invoice is worth now: the balance, plus the late fee your terms allow. Choose a one-off percentage, a flat amount, or a monthly charge.

The unpaid invoice

What is still unpaid, before any late fee.

Used only if you press Create this invoice, as the name of the balance line.

How overdue it is

The day it was due, not the day it was issued. The due date calculator works that out from your terms.

Today, or the day you expect to be paid.

Days after the due date before a fee starts. Leave at 0 if your terms have none.

The fee your terms allow

Charged once, however long the invoice stays unpaid.

The rate is yours to set. What you may charge, and whether it is enforceable at all, depends on where you are and on what the contract said before the work started.

GuideLate payment feesHow this works, and where the figures go wrong →

What this calculator does not do

  • It does not know what you are allowed to charge. Late fee caps, statutory interest and whether the fee is enforceable at all without a written term depend on your country and often on the state or province. Check yours, or ask someone who can be held to the answer.
  • It does not compound, does not add tax to the fee, and does not know whether the fee is taxable where you are — in some places it is, in others it falls outside the scope of the tax entirely.
  • It does not count public holidays or working days. Days past due are calendar days, which is how late payment terms are normally written.
  • It does not keep anything. Nothing is written to your browser's storage while you use it and nothing is sent to us, so the figures are gone when you close the tab. Press Create this invoice if you need a document: the balance and the fee are handed to the invoice generator in this tab as two lines, and cleared as soon as it opens.

Related

For interest running daily on the balance rather than a charge applied once, the late payment interest calculator does that one — a different instrument that often gets this one's name. To work out the due date this page needs, the invoice due date calculator takes the invoice date and your terms. For the invoice itself rather than what it has cost you to chase, the invoice calculator takes line items, a discount and a deposit.

Last updated 20 September 2026