No assessment shall be made or issued against a vendor or transient guest for any taxes imposed by or pursuant to this chapter more than four years after the return date for the period in which the lodging was furnished, or more than four years after the return for such period is filed, whichever is later. This section does not bar an assessment:
   (a)   When the Director of Finance has substantial evidence of amounts of taxes collected by a vendor from transient guest's lodging which were not returned to the City;
   (b)   When the vendor assessed failed to file a return as required.
(Ord. C41-76. Passed 5-17-76; Ord. C123-88. Passed 1-16-89.)