Net 30 Due Date Calculator

Invoice due date calculator

Use this invoice due date calculator to turn an invoice date and payment terms into a clear due date. It supports common calendar-day terms and optional business-day counting for contracts that exclude weekends or bank holidays.

When to use it

Use this for quick payment planning and invoice admin. Contract wording can vary, so check whether your terms mean calendar days, working days, end of month, or another rule.

What net 30 actually means

"Net 30" means payment is due 30 days after the invoice date. Unless the contract says otherwise, those are calendar days, not working days — so a weekend or bank holiday falling on the due date does not usually move it.

Example: an invoice dated 1 October 2026 on net 30 terms is due on 31 October 2026. An invoice dated 15 October is due on 14 November.

Calendar or business days?

Most net terms are calendar days, but not all. "30 working days" or "30 business days" terms exist, particularly in public-sector and construction contracts, and they produce a noticeably later date — around six weeks rather than four.

Check the wording on the invoice or contract before relying on a date. Where terms conflict, the contract normally governs.

If the invoice is paid late

For business-to-business debts, statutory late payment interest can run from the day after the due date at 8% above the Bank of England base rate, with fixed compensation on top depending on the size of the debt. The right depends on the terms and on both parties being businesses, so treat this as a prompt to check rather than a calculation.