Fill out the Business Tax Refund Request form when you need to get money back from the City for an overpayment. Was this page helpful?I overpaid my business tax. How do I request a refund? To request a refund for overpayment, follow these steps. Complete the Overpayment Refund Request Form. Thank you for reaching out to us. 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. If you feel you are due a refund, please fill out this form completely and legibly and provide proof(s) of payment. Your claim must state all of the following: The specific reasons you paid too much tax.