If the successor to the business fails to withhold a portion of the purchase price as required, he shall be liable for the payment of the amount required to be withheld. Within 30 days after receiving a written request from the successor for a certificate, the Director of Finance shall either issue the certificate or mail notice to the successor at his address, as it appears on the records of the Director of Finance, of the estimated amount of the tax and penalty that must be paid as a condition of issuing the certificate. The time period within which the obligation of a successor may be enforced shall commence at the time the operator sells or otherwise disposes of his business or at the time that the determination against the operator becomes final, whichever event occurs later, and shall expire, in the absence of fraud, three years thereafter. (Ord. 1471 § 1, 1973; Ord. 1339 § 1; prior code § 7.316).