ACH transactions will usually, but not necessarily always, be debited from the payer's account two business days from the date the ACH payment transmission is accepted. Business days now include federal holidays and bank holidays. Because banking institutions perform "electronic sweeps" at different times, it is not possible to guarantee that exactly two business days will elapse between the time of ACH payment authorization and the actual debit. The precise timing of an individual debit is determined solely by the ACH payer's bank. Certain payers' banks have been found, although infrequently, to debit accounts on Saturdays and Sundays. To avoid potential problems, the U.S. Customs and Border Protection National Finance Center very strongly urges all ACH payers to ensure that sufficient funds are available at the time each and every ACH payment transaction is authorized.