From spreadsheets to strategy: Tax modeling after the OBBBA

2026-04-20 · Source: Thomson Reuters Institute · Field: Finance & Economics — Corporate Finance & Treasury, Economic Analysis & Policy, Corporate Strategy & Leadership · Depth: Advanced, short

Summary

The One Big Beautiful Bill Act (OBBBA), signed in July 2025, significantly altered corporate tax landscapes by providing permanent full expensing for many investments, retroactively effective from mid-January 2025. This legislation restored 100% bonus depreciation, which was phasing out under the 2017 Tax Cuts and Jobs Act (TCJA), effectively reducing the after-tax cost of new capital assets by approximately 21%. While the OBBBA offers substantial tax benefits through permanent rate extensions, depreciation adjustments, and expanded SALT deduction caps, realizing these benefits requires corporate tax departments to rebuild their modeling capabilities to capture investment timing, location, debt-equity mix, and income booking. Many departments currently lack the sophisticated modeling and governance necessary to move beyond basic compliance and integrate these changes strategically, especially amidst external factors like the Iran war's impact on fuel and financing costs.

Key takeaway

For corporate tax directors and CFOs navigating the post-OBBBA environment, you must transition from spreadsheet-based compliance to disciplined, integrated tax modeling. This shift is critical to accurately capture tax benefits, manage liquidity, and proactively address macro-economic risks like the Iran war's impact on costs. By implementing robust governance and scenario planning, your department can earn a strategic seat at the table, moving beyond reactive cleanup to proactive value creation.

Key insights

Post-OBBBA tax modeling requires strategic integration, robust governance, and scenario planning beyond mere compliance.

Principles

• Tax departments must own the OBBBA model and narrative.
• Governance and analysis drive strategic influence, not just tools.
• External risks like geopolitical conflicts belong in tax models.

Method

Implement a unified tax model with standardized assumptions, conduct modeling reviews for major OBBBA-driven decisions, and explicitly document all assumptions to ensure accuracy and credibility.

In practice

• Create one integrated tax model for team use.
• Standardize key levers like capex timing and financing mix.
• Run war-extended scenarios with specific numbers.

Topics

• One Big Beautiful Bill Act
• Corporate Tax Modeling
• Full Expensing
• Tax Department Governance
• Strategic Tax Planning

Best for: Executive, Legal Professional, Consultant

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Editorial summary, takeaway, and curation by AIssential. Original article published by Thomson Reuters Institute.