Net 30

In contracts, this phrase specifies that payment is due within 30 days of a specific event, typically when the client receives the final artwork or invoice. It can be altered as you wish (i.e. Net 7, Net 15,) & the specific event could be from the start date of the project or upon signing the contract.

For instance, one could specify that 1/3 of the final fee is due Net 7 days after the initial briefing.