If any taxpayer fails to apply for a license or make his return, or to pay the fee or tax therefor, or the cost of any audit required by the City Clerk or any party thereof within 30 days after the same shall have become due, the City Clerk shall ascertain the amount of the fee or tax or installment, thereof and/or cost of audit due, and shall add to such amount a penalty of 12% of the amount, and shall notify such taxpayer therefor, who shall be liable therefor in any suit or action by the City for collection thereof. The City Clerk shall also notify the City Attorney in writing of the name of such delinquent taxpayer and the amount due from him and the City Attorney shall with the assistance of the City Clerk collect the same by any appropriate means or by any suit or action in the name of the City of George.