When a vendor issues a rebate check, it needs to be shown on the bank account without affecting the Vendor's account balance. Affecting their balance by issuing a credit will create a credit that can be used on future bills incorrectly. The easiest method is done via a journal entry.
These instructions will use an income account called reimbursed expenses, however you may elect to use another income account.
This journal entry will appear under the vendor's account in the Vendor Center; it will increase the bank balance by the amount of the refund as well as crediting (increasing) the balance on the income account to offset the post to the bank account.