Invoice due date calculator

Net terms count calendar days from the invoice date, not working days, and the invoice date itself is day zero. Net 30 on an invoice dated 3 March is therefore due 2 April, which is the kind of detail people get wrong by one day and then argue about.

The end-of-month option covers the other common convention, where terms run to the last day of the month in which the count lands. Some clients operate a fixed monthly payment run and will pay on that basis whatever your invoice says, so it can be worth matching their rhythm deliberately.

Shorter terms are not automatically better. What matters is whether the client's payment process can meet them: net 7 to an organisation with a monthly approval cycle is a term you will breach on their behalf every single month, which quietly trains everyone to ignore your due dates.

Pick terms that match how the client actually pays, write them on the document as a date rather than a phrase, and enforce them consistently. Consistency is what makes a follow-up feel like process instead of a favour.