California voters have rejected Proposition 40, the proposed one-time tax on billionaires' net worth. Decision Desk HQ projected the measure's defeat, with 54% voting no and 46% voting yes as of November 7, with about three-quarters of ballots counted, according to The Hill via NewsNation.
For the roughly 200 Californians who would have owed the tax, that is a relief. But the campaign leaves behind a useful question for family offices: if a tax authority asked you to state your family's total net worth on a single date, and stand behind the number, how long would it take to produce?
The measure would have imposed a one-time tax of 5% on the worldwide net worth of individuals worth $1 billion or more who lived in California on January 1, 2026. Net worth would have been measured as of December 31, 2026, with payment due in 2027 and an option to spread it over five years, according to Procopio.
The details show how complex the calculation could have become:
Public stocks are relatively easy to price on a given day. A minority stake in a private operating company, an LP interest in a venture fund or a co-investment held through several layers of entities is more complicated.
Advisors quoted by InvestmentNews noted that the measure's default valuation method could have produced values above what a business would actually sell for, while largely disallowing minority and illiquidity discounts. The alternative, a certified appraisal, can be expensive.
Then there are the structural questions. Which trusts are grantor trusts? Which assets are distributable to which beneficiary? Which gifts crossed the $1 million threshold, and when?
For many families, the answers are spread across a trust attorney's files, fund statements, spreadsheets and entity documents. Bringing that information together can be as difficult as calculating the final number.
The advisors InvestmentNews spoke to expect more state wealth tax proposals, regardless of what happened in California. Their advice applies more broadly: keep current valuations on closely held businesses, document residency, retain records and stress-test liquidity for families that are asset-rich and cash-poor.
A wealth tax is also only one example of a situation where a family may need a defensible net worth on a specific date. Estate settlements, divorces, lender covenant reviews, buy-sell agreements and gift tax returns can all require the same information.
Our explainer on data aggregation vs. reconciliation vs. consolidation covers what it takes to bring that picture together.
MYFO is a family office operating system that connects the entities, assets and liabilities, stakeholders and documents that make up a family's financial world. For families that want a net worth they can stand behind, MYFO supports:
MYFO works alongside a family's existing general ledger rather than replacing it, so the accounting stays where it is while the broader financial picture comes together.
Prop 40 won't become law. But families that can produce a clear picture of their wealth on a specific date will be better prepared for the next estate settlement, lender review or tax return that asks them to do the same.
Book a demo to see how MYFO helps families build a consolidated view of their wealth.
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