Calculation method
The due date is the invoice date plus the agreed number of calendar days. If a contract uses business days or has a public-holiday rule, calculate under that agreement instead.
Free LinkDuka tool
Enter an invoice date and agreed payment term to calculate the exact due date. Choose due on receipt or Net 7, 14, 30, 45, 60 or 90, then copy the date onto your invoice.
Quick answer: the due date is the invoice date plus the agreed number of calendar days. An invoice dated 1 March on Net 30 is due on 31 March; on Net 60 it is due on 30 April.
Add the agreed number of calendar days to the invoice issue date. For an invoice dated 1 March, Net 7 is due 8 March, Net 30 is due 31 March, and Net 60 is due 30 April. Due on receipt uses the invoice date. If your contract specifies business days or a different start date, follow that agreement. Use the calculator above to turn Net 7, 14, 30, 45, 60 or 90 payment terms into an exact date.
A clear invoice date, payment term, and due date prevent avoidable back-and-forth. They also help you plan cash flow and know when a polite payment reminder is reasonable.
Use terms that both sides understand before work starts or stock is delivered. Then include the exact due date beside the invoice total and payment instructions.
Start with the invoice issue date and add the agreed payment term in calendar days. For example, an invoice issued on 1 March with Net 30 terms is due 30 days later.
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How this tool works
A customer should not have to count days or interpret a phrase such as Net 30. Put the calculated date beside the invoice amount and payment instructions.
The due date is the invoice date plus the agreed number of calendar days. If a contract uses business days or has a public-holiday rule, calculate under that agreement instead.
An invoice issued on 5 August with Net 30 terms is due on 4 September. Show that exact date on the invoice rather than only writing Net 30.
Last reviewed: August 2026. Check your own agreement, invoice, or current official guidance before relying on a result for a transaction or tax return.
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