Illinois Statutes Chapter 35. Revenue § 638/40. Safe harbor

(a) If neither the State nor a designated database provider provides an electronic database under Section 25, a home service provider shall be held harmless from any tax, charge, or fee liability that otherwise would be due solely as a result of an assignment of a street address to an incorrect taxing jurisdiction if, subject to Section 60, the home service provider employs an enhanced zip code to assign each street address to a specific taxing jurisdiction for each level of taxing jurisdiction and exercises due diligence at each level of taxing jurisdiction to ensure that each such street address is assigned to the correct taxing jurisdiction. If an enhanced zip code overlaps boundaries of taxing jurisdictions of the same level, the home service provider must designate one specific jurisdiction within the enhanced zip code for use in taxing the activity for the enhanced zip code for each level of taxing jurisdiction. Any enhanced zip code assignment changed in accordance with Section 60 is deemed to be in compliance with this Section.

(b) For purposes of this Section, there is a rebuttable presumption that a home service provider has exercised due diligence if the home service provider demonstrates that it has: