Why would a business need to use more than one bank account?

There are many reasons for a business to have multiple bank accounts, depending on the size of the business. Most companies start with an Operating account, as the company grows, they may add a payroll account to keep their Operating funds and Payroll funds separate. As they continue to grow the would most likely add an investment account and change their operating account into a Sweep account. What this means is once their operating account gets above X number of dollars the surplus is "swept" (Transferred) into the investment account so the money can earn interest (most operating accounts do not pay any kind of interest). If the company receives alot of check payments by mail (like utility companies) they would also use a Lockbox account. When you send a payment to a PO Box, those payments are heading to a bank to be processed and usually aren't handled by the company you are paying. The bank will process the mail and deposit the funds into an account, and send a report showing who has sent in payment back to the company. This is just a small portion of the types of accounts a business may want or need as it grows in size