All taxes imposed by this chapter shall be collectible, together with any interest and penalties thereon, by suit, as other debts of the like amount are recoverable. Except in the case of fraud, of omission of a substantial portion of income subject to this tax, or of failure to file a return, an addition assessment shall not be made after three years from the time the return was due or filed, whichever is later, provided, however, in those cases in which a Commissioner of Internal Revenue and the taxpayer have executed a waiver of the Federal Statute of Limitations, the period within which an additional assessment may be made by the Administrator shall be one year from the time of the final determination of the federal tax liability. (Ord. 62-1995. Passed 7-3-95.)