All real property included within, or excluded from, a district shall thereafter be subject to the levy of taxes for the payment of any indebtedness of the district outstanding at the time of inclusion or exclusion; provided, however, that after any real property shall have been excluded from a district, as provided in section 247.530, any buildings and improvements thereafter erected or constructed on said excluded real property, and all machinery and equipment thereafter installed or placed therein or thereon, and all tangible personal property not in said district at the time of the exclusion of said real property from said district which shall thereafter be situate on or used in connection with said real property, shall not be subject to any taxes levied by said district.