TAXATION – Amends existing law to update references to the current Internal Revenue Code and to revise certain tax credits and adjustments.
House Bill 559 updates Idaho’s tax code to conform to the Internal Revenue Code as amended and in effect on January 1, 2026, rather than January 1, 2025, with specific exceptions. It preserves Idaho’s special treatment of certain federal provisions, including section 85 and specified research and experimental expenditures, and it directs that certain research costs incurred in taxable years beginning on or after January 1, 2022, and before January 1, 2025, continue to be expensed under preexisting federal rules rather than under later federal changes.
The bill also revises Idaho’s rules for bonus depreciation and related basis adjustments under section 63-3022O. It clarifies how Idaho taxpayers must add back and later recover bonus depreciation when federal loss limitations delay use of those deductions, including special rules for pass-through entities, part-year residents, and nonresidents. The bill extends the period for assessments and refunds tied to these adjustments and requires taxpayers to maintain records showing Idaho basis, at-risk amounts, and loss carryovers to prevent double tax benefits.
In addition, H0559 modifies Idaho’s research activities credit under section 63-3029G. The credit remains a nonrefundable credit equal to 5 percent of qualifying Idaho research expenses above a base amount plus 5 percent of qualifying basic research payments, but the bill updates the federal references used to define those expenses and clarifies that amounts deducted or amortized under federal sections 174 or 174A cannot also generate the Idaho credit. It also preserves the 14-year carryforward period and allows the State Tax Commission to adopt attribution rules for pass-through entities.
The bill’s impact is primarily technical but financially significant for taxpayers, especially businesses with research spending, depreciable property, or pass-through entity structures. It conforms Idaho law to current federal tax definitions while carving out Idaho-specific exceptions intended to control timing and prevent unintended windfalls from federal depreciation and research expensing changes. The act is retroactive to January 1, 2025, and was enacted as an emergency measure, meaning it applies immediately upon passage and approval.
The overall sentiment appears broadly favorable and pragmatic, as reflected by strong bipartisan support in both chambers and final enactment. The votes were 57-8 in the House and 28-7 in the Senate, suggesting general agreement on the need to update Idaho’s tax conformity rules. The main points of contention likely centered on the retroactive effective date, the treatment of bonus depreciation and loss limitations, and the exclusion of certain federally deducted research costs from Idaho’s research credit, all of which affect taxpayer liability and compliance timing.
H0559 amends Idaho Code sections 63-3004, 63-3022O, and 63-3029G to update Idaho’s conformity to the Internal Revenue Code, revise depreciation and loss-adjustment rules, and adjust the state research activities credit. It affects individual and business taxpayers, especially those claiming bonus depreciation, operating through pass-through entities, or claiming Idaho research credits. The bill also extends limitation periods for related assessments and refunds and applies retroactively to January 1, 2025.
The bill appears to have been viewed as a routine but important tax conformity measure, with substantial support in both the House and Senate. The recorded votes indicate broad acceptance of the bill’s technical updates and fiscal clarifications. Any opposition seems limited and likely focused on the retroactive application and the specific tax-base and credit changes rather than the overall need to conform state law to updated federal provisions.
The most notable areas of contention are the retroactive effective date, the treatment of federal bonus depreciation and suspended losses, and the restriction that amounts deducted or amortized under federal sections 174 or 174A cannot also qualify for Idaho’s research credit. Taxpayers with research-intensive operations, pass-through entities, or significant capital investments may be most affected by these provisions, since they alter timing, recordkeeping, and the availability of state tax benefits. The bill also raises compliance concerns by requiring detailed tracking of Idaho basis and loss carryovers to avoid double deductions or double inclusion of income.