Invoice Due Date & Late Fee Calculator
See when an invoice is due under your payment terms and what late fee to charge if it's overdue. Plan your cash flow and enforce terms with confidence. 100% in your browser.
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Invoice Terms & Late Fee
All calculations are processed locally in your browser. No data is uploaded, stored, or shared with any server. 100% private and secure.
Invoice
Unpaid invoice amount before any fee.
Late Fee
e.g. 1.5% per month, prorated by days overdue.
Your Invoice Timeline
Choose an invoice date and enter the amount to see the due date and any late fee.
This calculator provides estimation only. All results are for reference purposes only and do not constitute professional tax, financial, or legal advice. Please consult a qualified professional for official financial decisions.
Get Paid Faster and Enforce Your Terms
Payment Terms Are a Cash-Flow Tool
The date an invoice is due is not a formality—it is the single biggest lever you have over your cash flow. Net 30 terms on a $5,000 invoice mean financing your client for a month. Knowing the exact due date, and having a late fee ready when it passes, keeps your receivables from quietly becoming an interest-free loan.
A Late Fee That Works Starts at the Contract
The most enforceable late fee is the one the client agreed to before the work began. Write your terms and fee into your proposal or contract, repeat them on the invoice, and apply them consistently. Most freelancers use 1–1.5% per month or a flat fee, but local law may cap what you can charge, so confirm before you set your rate.
How Overdue Fees Are Calculated
Overdue days are counted from the day after the due date. A monthly percentage is usually prorated by the actual days overdue on a 30-day month, a daily percentage multiplies the amount by the rate for each day, and a flat fee is charged once. This calculator applies the convention you choose and shows the total the client owes.
How to Use This Calculator
Enter the invoice amount and date, pick your payment terms, and choose your late fee structure. The calculator shows the due date, whether the invoice is overdue today, the fee that applies, and the total amount due—so you can send a precise reminder without doing the math by hand.
Frequently Asked Questions
Answers to common questions about using this calculator.