Promissory notes are a common financial instrument in many jurisdictions, employed principally for short time financing of companies. Often, the seller or provider of a service is not paid upfront by the buyer (usually, another company), but within a period of time, the length of which has been agreed upon by both the seller and the buyer. The reasons for this may vary; historically, many companies used to balance their books and execute payments and debts at the end of each week or tax month; any product bought before that time would be paid only then. Depending on the jurisdiction, this deferred payment period can be regulated by law; in countries like France, Italy or Spain, it usually ranges between 30 and 90 days after the purchase.