You may file a claim for refund using CDTFA's online services. To submit a claim for refund, simply login using your username and password.A claim for refund is a request for reimbursement of amounts previously paid. Generally, if you have paid your balance in full you will file a formal claim. In this article, we'll show you how to write a refund request letter template that not only grabs attention but also persuades companies to act in your favor. If you believe you have overpaid an amount and you wish to receive a refund of the overpaid amount, you must file a claim for refund with the CDTFA. Begin the filing process as you would with any other filing and select "Request for Refund" as the Document Type from the list of options in the dropdown. Some of the more common reasons for refunds are: The first installment of a two installment tax bill was overpaid or paid twice. Refund request may take up to 2 months to process. Approved refunds will be processed in payment method selection.