Invoice Late Fee Calculator

Charging Late Fees on Overdue Invoices

Dealing with late payments is one of the most frustrating aspects of running a freelance business or agency. Implementing a strict, enforceable late fee policy is the best way to ensure clients prioritize your invoices.

Standard Commercial Interest Rates

You cannot simply invent a punitive number out of thin air. In most jurisdictions, courts will only enforce "reasonable" interest rates that compensate you for the delay in payment, rather than punishing the client.

• United States: Depending on the state, standard B2B commercial late fee interest is usually capped between 8% and 18% annually (often expressed as 1.5% per month).
• United Kingdom: The Late Payment of Commercial Debts (Interest) Act allows businesses to charge the Bank of England base rate plus 8%, along with a fixed administrative sum for the cost of recovering the debt.
• European Union: The Late Payment Directive allows for the European Central Bank reference rate plus 8%.

How the Calculation Works

Because standard commercial rates are expressed annually (APR), you must divide the annual rate by 365 to find the daily interest rate, and then multiply that by the exact number of days the invoice is overdue.

Best Practices for Enforcing Late Fees

• Include it in your contract: You generally cannot charge a late fee if it was not explicitly stated in the Master Services Agreement (MSA) or the invoice itself before the work began.
• Send a 3-day grace period reminder: Before applying the fee, send a polite but firm reminder 1-3 days after the due date. Frame the fee as an automated system process rather than a personal attack.
• Be willing to waive it once: If a good client makes a genuine mistake, waiving the first late fee as a "courtesy" can build tremendous goodwill, while still establishing that you enforce your boundaries.