4 U.S.C. § 120 — Procedure if no electronic database provided

(a) Safe Harbor. If neither the state nor a designated database provider gives phone companies ("home service providers") the electronic database described in section 119, a company is protected from tax, charge, or fee liability that would otherwise result solely from assigning a street address to the wrong taxing jurisdiction. To get this protection, the company must use an "enhanced zip code" to assign every street address to a specific taxing jurisdiction at each level of government, and must use due diligence at each level to get the jurisdiction right (subject to section 121). If an enhanced zip code straddles the boundary between two jurisdictions of the same level, the company must pick one specific jurisdiction within that zip code to use for tax purposes at that level. Any enhanced zip code assignment that gets changed under section 121 automatically counts as compliant. There's a rebuttable presumption — meaning it's assumed true unless proven otherwise — that a company used due diligence if it shows all three of the following: (1) it spent reasonable resources building and maintaining a properly detailed database of street-address-to-jurisdiction assignments; (2) it kept reasonable internal controls in place to quickly fix misassigned addresses; and (3) it used all reasonably available and usable data about things like city annexations, incorporations, and reorganizations that would materially change which addresses belong to which jurisdiction. (b) Termination of Safe Harbor. This protection lasts, for a state that hasn't yet provided a section 119 database, until the later of two dates: 18 months after the Federation of Tax Administrators and the Multistate Tax Commission approve the nationwide standard numeric code described in section 119(a); or 6 months after the state (or its designated database provider) actually provides that database.