In this title, “property tax” includes a taxing district tax. For purposes of this title, property newly annexed into a municipal corporation during a period shall be treated as initially added to the tax roll for that period. The imposition of the municipal property tax for a partial year on property newly annexed into a municipal corporation shall have no effect on the tax setoff under § 6-305 or § 6-306 of this article. Expenses incurred by a county for billing and collecting municipal corporation property taxes for a partial year on property newly annexed into the municipal corporation shall be chargeable to the municipal corporation for which the property taxes are collected.