On Oct. 21, 2025, the 2026 Billionaire Tax Act was filed with the California Attorney General’s office. The proposed initiative, if enacted, will impose a one-time 5% excise tax on California residents with net wealth in excess of $1 billion, to be paid April 15, 2027.
Proponents of the measure will begin circulating it for signatures in an effort to qualify it for the November 2026 California ballot. They need to gather roughly 900,000 verifiable signatures to be successful.
Who could be impacted by the proposed billionaire’s tax?
The proposed ballot measure, if passed, would impact California resident individuals, whether single or married, with a net worth over $1 billion in 2026. The proposed measure would also impact trusts with California resident beneficiaries that cross the same net worth threshold. The measure, if passed by the voters, would be retroactive to Jan. 1, 2026.
How would net worth be determined?
Under the terms of the proposed ballot measure, net worth would be determined by taking the fair market value of all assets owned by the taxpayer, including assets held in grantor trusts, with limited exceptions. The proposed measure is explicit that a forced sale price or sale price in a market outside of the normal channels, such as selling silver on a coffee exchange, would not count for determining market value. Instead, the burden would be upon the taxpayer to demonstrate the fair market value of each of their assets to the satisfaction of the Franchise Tax Board.
Notably, interests in real property, whether held directly or through a trust, and certain retirement accounts are excluded for determining net worth for purposes of the potential tax. The proposed measure would also exclude tangible personal property located outside of California for more than 270 days in 2026 so long as the purpose was not to avoid tax.
The assets to measure would include stock, partnerships, interests in business entities, any equity interests, ownership interests, debt interests, and “all other contractual or noncontractual interests” the taxpayer may own.
The information provided here is of a general nature and is not intended to address the specific circumstances of any individual or entity. In specific circumstances, the services of a professional should be sought. Tax information, if any, contained in this communication was not intended or written to be used by any person for the purpose of avoiding penalties, nor should such information be construed as an opinion upon which any person may rely. The intended recipients of this communication and any attachments are not subject to any limitation on the disclosure of the tax treatment or tax structure of any transaction or matter that is the subject of this communication and any attachments.

