Whenever one or more special transit service districts are created and established pursuant to Chapter 10.5 (commencing at Section 27401), taxes in excess of one cent ($0.01) per one hundred dollars ($100) of assessed valuation shall not thereafter be levied against any property not within the boundaries of a special transit service district, excepting, however, taxes sufficient to pay the principal or interest or both on any bonded indebtedness theretofore or thereafter incurred by a district as a whole. The creation of a special transit service district does not invalidate, in any manner, any taxes or assessments previously levied or assessed against any property of the
district, either within or without the boundaries of a special transit service district.