Regular customers are sent periodic statements stating the opening balance, record of invoices, payments made, debit memos, credit memos and the ending balance for a specific period.  Some companies issue a monthly statement to serve as an invoice to request a single payment from a customer.

An invoice can also be issued weekly or monthly when a customer purchases goods regularly in small amounts.  The delivery receipts are issued for every delivery or withdrawal of goods and these are totalled weekly or monthly so that a single invoice can be prepared at the end of the agreed upon period.