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Read. Follow. Verify.Idaho House Bill 559 Updates Internal Revenue Code Conformity and Revises Tax Adjustments
Last action · February 11, 2026: Reported Signed by Governor on February 10, 2026 Session Law Chapter 1 Effective: Retroactive to 01/01/2025
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What This Bill Does
Idaho House Bill 559 updates state tax references to the current Internal Revenue Code as of January 1, 2026, revises adjustments, modifies research and development tax credit carryforwards, and applies retroactively to January 1, 2025.
Taxpayers and businesses filing Idaho income tax returns must calculate their state taxable income and research credits using newly updated federal code definitions and adjusted depreciation rules.
- Idaho regularly updates its state tax code references to conform with annual changes made to the federal Internal Revenue Code. context
Who It Affects
Groups the bill's text affects, as described in the record. Being affected is not a position for or against it.
Taxpayers
Taxpayers must compute their Idaho taxable income and tax adjustments using the updated Internal Revenue Code references and revised depreciation rules.
Pass-through entities
Partners, shareholders, members, and beneficiaries must include their share of required adjustments and maintain records of Idaho tax basis and loss limitations.
Key Facts
- The term 'Internal Revenue Code' is updated to mean the code as amended and in effect on January 1, 2026.
- Internal Revenue Code section 85 is applied as in effect on January 1, 2020.
- Specified research or experimental expenditures under section 174 incurred in taxable years before January 1, 2025, continue to be expensed under provisions in effect prior to section 70302 of P.L. 119-21.
- Adjusted basis of depreciable property acquired after September 10, 2001, shall be computed without regard to bonus depreciation under subsections (k) and (n) of section 168, subject to loss limitations and suspension rules.
Show all 7 facts
- Excess research activity credits for research conducted in Idaho may be carried forward for a period not to exceed the next fourteen (14) taxable years.
- For a group of corporations filing a combined report, credit earned by one member may be used by another member of the group.
- The act is declared an emergency and is effective upon passage and approval, retroactively to January 1, 2025.
Frequently Asked Questions
What does House Bill 559 change regarding the Internal Revenue Code?
How long can unused research tax credits be carried forward under this law?
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News Coverage
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Votes, people, money & the original sourceWhere This Stands
Current status: Signed into law.
Procedural history
16 actions- Feb 11, 2026EnrolledReported Signed by Governor on February 10, 2026 Session Law Chapter 1 Effective: Retroactive to 01/01/2025
- Feb 10, 2026Delivered to Governor at 2:40 p.m. on February 9, 2026
- Feb 9, 2026Returned Signed by the President; Ordered Transmitted to Governor
- Feb 9, 2026Signed by President; returned to House
- Feb 9, 2026Received from the House enrolled/signed by Speaker
- Feb 9, 2026Reported Enrolled; Signed by Speaker; Transmitted to Senate
Show 10 earlier actions
- Feb 9, 2026FloorReturned from Senate Passed; to JRA for Enrolling
- Feb 6, 2026FloorRules Suspended (2/3 Vote - Read in full as required) – PASSED - 28-7-0 AYES – Adams, Anthon, Bernt, Bjerke, Blaylock, Burtenshaw, Carlson, Cook, Den Hartog, Foreman, Galloway, Grow, Harris, Hart, Keyser, Kohl, Lakey, Lenney, Lent, Nichols, Okuniewicz, Ricks, Shippy, Toews, VanOrden, Woodward, Zito, Zuiderveld NAYS – Guthrie, Rabe, Ruchti, Semmelroth, Taylor, Ward-Engelking, Wintrow Absent and excused – None Floor Sponsor - Ricks Title apvd - to House
- Feb 6, 2026Reported out of Committee with Do Pass Recommendation; Filed for second reading
- Feb 4, 2026IntroducedIntroduced, read first time; referred to: Local Government & Taxation
- Feb 4, 2026FloorReceived from the House passed; filed for first reading
- Feb 3, 2026FloorRules Suspended: Ayes 64 Nays 2 Abs/Excd 4, read in full as required – PASSED - 59-9-2 AYES – Barbieri, Beiswenger, Bingham, Boyle, Bruce, Burgoyne, Cannon, Cayler, Cheatum, Cornilles, Crane(12), Crane(13), Dygert, Ehardt, Ehlers, Erickson, Fuhriman, Furniss, Garner, Hall(Stone), Handy, Harris, Hawkins, Healey, Hill, Holtzclaw, Hostetler, Leavitt, Manwaring, Marmon, McCann, Mendive, Mickelsen, Miller, Mitchell, Monks, Nelsen, Palmer, Petzke, Pickett, Pohanka, Price, Rasor, Raybould, Raymond, Redman, Sauter, Scott, Shepherd, Shirts, Skaug, Tanner(13), Tanner(14), Vander Woude, Veile, Weber, Wheeler, Wisniewski, Mr. Speaker NAYS – Berch, Church, Egbert, Galaviz, Gannon, Green, Haws, Mathias, Rubel Absent – Alfieri, Thompson Floor Sponsor - Ehlers Title apvd - to Senate
- Feb 3, 2026Read second time; Filed for Third Reading
- Feb 2, 2026Reported out of Committee with Do Pass Recommendation, Filed for Second Reading
- Jan 30, 2026CommitteeReported Printed and Referred to Revenue & Taxation
- Jan 29, 2026IntroducedIntroduced, read first time, referred to JRA for Printing
Version history
Only one version on file - nothing to compare yet. As later stages (committee substitute, engrossed, enrolled) are captured, the redline appears here.
View official text →Lobbying Activity
No state lobbying filings in our records match this bill. Federal lobbying reports (LDA) cover Congress, so they are not listed on state bills.
Full breakdown
Who this bill affects and the strongest case for and against it, written only from the bill’s own text.
Discoveries
Patterns POLISCOPE noticed across the record. These are observations to investigate, not conclusions.
Retroactive Tax Application
The legislation applies retroactively to January 1, 2025, ensuring continuous alignment with preceding tax periods.
Connected Entities
Sources
legislature.idaho.gov
Analysis Score
0–100- Significance75How much this matters to a regular citizen
- Controversy15Intensity of disagreement among stakeholders
- Entertainment5Compellingness for a non-policy-wonk reader
- Buzz20Current news / social attention level
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