The principle purpose of a voucher system is to provide assurance that all cash payments are approved before a check is issued.
 
 A voucher system is a way of internally controlling that helps prevent fraudulent withdrawals from a company by employees or people outside the organization. 
 
 A voucher system organizes procedures to verify and approve cash disbursements, which is important because cash is vulnerable to theft. The voucher system helps guard a company's cash.