The 2026 tax season arrives during a time of significant change for large businesses. Sweeping federal reforms, new global tax standards, evolving clean energy incentives, and a modernizing IRS are reshaping the compliance landscape. To avoid costly missteps and capitalize on new opportunities, businesses must stay informed about regulatory changes and adopt robust, technology-driven compliance strategies. Here’s a comprehensive guide to help you navigate this tax season effectively.
1. Federal Tax Overhaul: The One Big Beautiful Bill Act (OBBBA)
The One Big Beautiful Bill Act (OBBBA), enacted in July 2025, represents the most significant overhaul of the U.S. tax code in years. Its provisions impact nearly every aspect of business taxation, from deductions and credits to reporting and compliance.
Key Changes to Know
- Full Expensing for Domestic R&D and Qualified Property
- Domestic R&D Expensing: Businesses can now fully deduct qualifying domestic R&D expenses in the year incurred, eliminating the need to capitalize and amortize these costs. This change applies to tax years beginning after December 31, 2024, and is a game-changer for innovation-driven companies.
- 100% Bonus Depreciation: Businesses can deduct the full cost of qualifying assets placed in service after January 19, 2025, including new and used property. For example, a manufacturer investing $50 million in equipment upgrades in 2026 can deduct the entire amount, improving cash flow and after-tax returns.
- Interest Expense and QBI Deduction
- Section 163(j) Limitation: The EBITDA-based calculation for the business interest expense limitation is permanently restored, allowing more interest to be deducted—especially beneficial for capital-intensive businesses.
- Qualified Business Income (QBI) Deduction: The 20% QBI deduction for pass-through entities is now permanent, providing ongoing tax relief for partnerships and S corporations.
- Charitable Contributions and Reporting Requirements
- Charitable Contributions Floor: For C Corporations, only contributions exceeding 1% of taxable income are deductible, with a 10% ceiling. Businesses should consider “stacking” contributions in a single year to maximize the benefit.
- Enhanced Reporting: The Form 1099 reporting threshold for nonemployee compensation is raised to $2,000, and the $20,000/200 transaction threshold for Form 1099-K reporting is reinstated.
Best Practice:
Conduct a thorough review of your accounting methods and fixed asset schedules. File Form 3115 for any required method changes, and ensure all eligible R&D and capital expenditures are properly documented and expensed.
2. International Tax Developments: Pillar Two and Global Minimum Tax
The global tax environment is undergoing a seismic shift with the implementation of the OECD’s Pillar Two global minimum tax, which ensures large multinational enterprises (MNEs) pay at least a 15% effective tax rate in every jurisdiction.
Pillar Two Compliance
- Scope: Applies to MNEs with annual consolidated revenue of €750 million or more. Over 60 countries are enacting these rules, with the first GloBE Information Return (GIR) due as early as June 2026 in some jurisdictions.
- Key Mechanisms: Includes the Qualified Domestic Minimum Top-Up Tax (QDMTT), Income Inclusion Rule (IIR), and Undertaxed Profits Rule (UTPR). U.S.-parented groups may benefit from exemptions under the G7 “side-by-side” agreement, but reporting requirements remain extensive.
- Data Readiness: Compliance requires granular, country-by-country data, including deferred tax accounting, permanent and temporary differences, and detailed entity-level information.
U.S. International Tax Changes under OBBBA
- GILTI and FDII Reforms: GILTI is now “net CFC tested income” (NCTI), and FDII is renamed “foreign-derived deduction eligible income” (FDDEI). Both have new calculation methods and reduced deductions, broadening the tax base.
- Foreign Tax Credit (FTC) Changes: The haircut on indirect FTCs for NCTI is reduced from 20% to 10%, and new sourcing rules allow up to 50% of income from U.S.-produced inventory sold abroad to be treated as foreign-source.
Best Practice:
Establish a cross-functional compliance team, including tax, finance, IT, and legal. Invest in technology to automate data collection and reporting and conduct a “dry run” of the GloBE Information Return to identify data gaps.
3. Clean Energy Credits and Incentives: New Restrictions and Deadlines
The OBBBA has reshaped clean energy incentives, introducing stricter eligibility requirements and accelerated phase-outs.
Key Changes
- Wind and Solar Credits: To qualify for Section 45Y and 48E credits, construction must begin by July 5, 2026, or facilities must be placed in service by December 31, 2027. The Five Percent Safe Harbor is eliminated, leaving only the Physical Work Test.
- Foreign Entity Restrictions: Projects with significant ownership or control by specified foreign entities (e.g., China, Russia) are disqualified from credits.
- Advanced Manufacturing and Clean Fuel Credits: Section 45X credits for wind energy components phase out after 2027, while Section 45Z clean fuel credits now require feedstocks to be sourced from the U.S., Mexico, or Canada.
Best Practice:
Review your supply chain, ownership, and financing structures to ensure compliance with material assistance and foreign entity rules. Document all sourcing and contractual relationships to support credit claims.
4. IRS Enforcement and Digital Transformation
The IRS is modernizing its operations with increased funding, new technology, and a focus on data-driven enforcement.
What to Expect
- AI-Driven Audits: The IRS is using artificial intelligence to identify high-risk returns, with a focus on transfer pricing, executive compensation, and clean energy credits.
- E-Filing Mandates: Lower thresholds for e-filing mean more businesses must comply with electronic filing requirements.
- Real-Time Communication: Expanded online services include secure messaging, digital notices, and electronic payment options.
Best Practice:
Centralize documentation, update internal controls, and conduct mock audits to identify and address weaknesses. Ensure your tax technology stack is integrated and compliant with new e-filing mandates.
5. State and Local Tax Conformity: A Patchwork of Rules
States are responding differently to OBBBA provisions, creating a complex compliance environment for multistate businesses.
Key Considerations
- Decoupling from Federal Changes: Some states have decoupled from federal R&D expensing and bonus depreciation, requiring separate calculations for state and federal returns.
- Remote Work and Nexus: Track employee locations, sales, and property to determine filing obligations and apportionment factors.
- State Credits and Incentives: Many states are expanding transferable tax credit programs, especially for clean energy and affordable housing.
Best Practice:
Monitor state legislative developments and use tax technology to track conformity, apportionment, and credit opportunities. Coordinate with state and local tax advisors to optimize your filing positions.
Practical Steps for a Smooth Tax Season
- Start Early: Conduct a year-end tax review to identify planning opportunities and compliance risks.
- Invest in Technology: Automate data collection and integrate tax systems to ensure accuracy.
- Strengthen Documentation: Maintain contemporaneous records for all credits, deductions, and cross-border transactions.
- Engage Advisors: Work with tax professionals to interpret new guidance and prepare for increased audit scrutiny.
- Conduct Mock Audits: Test your readiness in high-risk areas like transfer pricing and clean energy incentives.
Conclusion
The 2026 tax season presents both challenges and opportunities for large businesses. By staying informed, investing in technology, and strengthening compliance processes, your organization can turn tax compliance into a strategic advantage. Start early, stay proactive, and work closely with your advisors to ensure a smooth and successful tax season.
