Invoice Late Fee Calculator
Calculate late-payment interest on an overdue US invoice using a standard 1.5%-a-month contractual rate — the US has no single federal statutory rate.
Total amount due
$5,000
Days overdue0
Interest accrued$0
Statutory rate applied18.0%
Calculating Late-Payment Interest on a US Invoice
Unlike the EU's Late Payment Directive or the UK's statutory late-payment rate, the United States has no single federal law setting a default interest rate for a late invoice between private businesses. The federal Prompt Payment Act does set a rate — but it only governs what the US government itself owes its own contractors, not private B2B invoices. This calculator uses the most common contractual default seen on US invoice templates instead.
What you should know before charging a late fee
- There is no federal statutory late-payment interest rate for private B2B invoices — whatever rate you charge needs to come from your contract or payment terms, bounded by your state's usury law where no rate was agreed
- This calculator defaults to 18% per year (1.5% per month), which is the most common contractual convention used on US invoice templates and terms of service — it's an illustrative default, not a legal requirement
- Some states have their own prompt-payment acts, but they're mostly limited to public-sector or construction-industry payments rather than general commercial invoices
- Always check that your invoice or contract actually states a late-fee rate in writing before charging one — without an agreed term, you may be limited to your state's default legal interest rate instead
