The California Billionaire Tax Act: Delayed, Contested, And Uncertain Revenue

The 2026 Billionaire Tax Act (“BTA”) asks policymakers to rely on revenue that may be slow, contested, and uncertain. The Act’s own design creates four practical problems: (1) court challenges could delay collection for years; (2) residency disputes could make enforcement difficult; (3) even complying taxpayers may pay over time; and (4) the Optional Deferral Account rules could push payment even further into the future. In short, the BTA may be sold as a near-term funding solution, but its design makes timely and reliable collection far less certain.

• Court Challenges Could Delay Any Real Budget Benefit: The BTA is likely to face immediate constitutional challenges. That means California could spend years defending the tax before it sees meaningful revenue—if it sees that revenue at all.
  • A court could stop collection while the case is being litigated.
  • Because the Act raises serious constitutional questions and is likely to be challenged immediately, final resolution could take years.
• Residency Disputes Could Significantly Undermine the Tax: The Act turns on who was a California resident on January 1, 2026. That question is often disputed and highly fact specific. And this is not a remote concern: the Legislative Analyst’s Office (“LAO”) itself concluded that it is likely some billionaires would leave California in response to the tax, reducing ongoing state income tax revenue by hundreds of millions of dollars or more per year. If taxpayers contest residency, California may be forced into costly, case-by-case disputes over who is subject to the tax.
  • Billionaires have strong incentives to make a good faith argument that they left California before the State could constitutionally impose the BTA tax on them, particularly given the Act’s January 1, 2026 residency trigger and the constitutional questions that timing creates. The LAO already recognized that some departures are likely, and we are aware of individuals in this group who have left or are preparing to leave.
  • If taxpayers do not self-report, the state may face expensive, individualized disputes over residency and valuation. That would make collections harder to administer, slower to realize, and less predictable than the headline estimates suggest.
• Even Complying Taxpayers May Pay Slowly: The Act does not require full payment up front. It allows taxpayers to pay in five annual installments. So even in the best-case scenario—survival in court and taxpayer compliance—the revenue would still arrive only over time.
• The ODA Rules Could Push Collection Even Further Out: For certain taxpayers, the Act allows use of an Optional Deferral Account (“ODA”). That means part of the tax may not be paid unless and until later sales, distributions, or other triggering events occur.
  • In practice, that could delay collection for many years.
  • Because ODA payments depend on future transactions and future asset values, actual collections could fall materially below the headline estimate.

California should be cautious about relying on revenue that may be delayed by litigation, contested in enforcement, and collected only over many years. Whatever one thinks of taxing wealth as a policy matter, the BTA is not a reliable near-term funding solution and should not be treated as one.

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