AZ HB2583

Amends section 42-1001 to update the definition of "internal revenue code" to mean the U.S. Internal Revenue Code of 1986 as amended and in effect as of January 1, 2019 (changed from January 1, 2018).

Amends section 43-105 to add a new subsection A establishing internal revenue code conformity for taxable years beginning after December 31, 2018, using the January 1, 2019 version of the code.

Renumbers existing subsections B through K in section 43-105 to accommodate the new subsection A.

Includes provisions to incorporate retroactive effective dates from the Bipartisan Budget Act of 2018 (P.L. 115-123) and the Consolidated Appropriations Act, 2018 (P.L. 115-141) for taxable years 2017-2018.

Applies similar retroactive effective date provisions for the Consolidated Appropriations Act, 2018 across multiple taxable year periods in the amended statute.