If any taxpayer fails, neglects or refuses to make and file his return as and when required under these provisions, the city clerk-treasurer is authorized to determine the amount of tax payable, together with any penalty and/or interest assessed. The taxpayer shall then be notified by mail of the amount which shall become immediately due and payable. (Ord. 456 § 1, 2012; Ord. 203 § 10, 1980)