Voucher as evidence of payment and authority for disbursement, certifying correctness of accounts and discharge. A voucher is a written instrument functioning as a receipt, acquittance, or release serving as evidence of payment or discharge of a debt and certifying correctness of accounts; it may be an account book of acquittances and, for disbursements, is a bill of particulars, account, receipt, or acquittance showing the fact, authority, and purpose of the disbursement.