Location-based reporting
In short
Reporting income to the jurisdiction it belongs to. For a contractor that is the job site, which is usually not the business's own location.
In full
Arizona collects transaction privilege tax for the state, the counties and the cities on one return, so every line has to say which jurisdiction it belongs to. That is what location-based reporting means.
Two different numbers do two different things, and the names are close enough to cause trouble.
A location code identifies a registered business location. ADOR assigns one to each location on a TPT license, and it appears on the license certificate as a three-digit number below the address.
A region code identifies the taxing jurisdiction an amount is reported to. It is what the transaction detail page and Schedule A actually take.
For most businesses the two line up, because income arises where the business is located. For a contractor they routinely do not. Prime contracting income is reported to the location of the project, and the retail equivalent on MRRA materials is reported to the job site. A contractor with one office working in six jurisdictions files six region rows and never reports to the office at all.
ADOR's own page on the subject addresses location codes for business locations and does not discuss contracting.
ADOR Location Based Reporting; ADOR Modification Contracting; ADOR MRRA Contracting; A.R.S. § 42-5075