When should an invoice be issued?

Any company that sells to non-consumers should issue an invoice to the buyer at the time an order is placed or a purchase transaction takes place. In some cases, companies send invoices at the start, middle or end of a month instead of at the time of each purchase.

Thomsen Business Information indicates that if a company doesn't issue an invoice on the actual transaction date, it should allow for no more than a two-week lag between purchase date and invoice date. A prompt invoice is important for accounting purposes as well as to ensure timely payment from a company's customers.