California’s wealthiest residents are scrambling to shield their fortunes as November comes closer with the controversial billionaire tax — with some accelerating charitable donations, buying luxury vacation homes and even joking about divorce to soften the blow.

The proposed measure, if passed, would impose a one-time levy of up to 5% on the net worth of Californians worth more than $1.1 billion, based on their wealth at the end of this year if they were state residents on Jan. 1.

Lower rates would gradually phase in for fortunes just above the $1 billion mark.

That prospect has triggered a flurry of calls to tax advisers, estate planners and attorneys as billionaires and near-billionaires search for ways to reduce their exposure or avoid the tax altogether.

Some wealthy Californians have already left the state, while others are determined to stay and instead rearrange their finances.

Veteran tax and estate adviser Andrew Katzenstein told the Wall Street Journal that one longtime client — a real estate investor with deep ties to California — has no plans to move despite concerns over the proposal.

The investor and his advisers have been examining ways to make his finances more “tax-efficient,” including speeding up charitable giving plans that he and his wife had already been considering.

“People take steps to take advantage of the tax law before it changes all the time. This is just another example of that,” said Katzenstein, a partner at accounting firm HCVT who is advising multiple clients on the proposal.

The investor has already donated hundreds of millions of dollars to charity over the years and believes additional giving would be preferable to handing more money to Sacramento, according to Katzenstein.

Other wealthy residents are considering more unconventional moves.

Jon Feldhammer, managing partner of the San Francisco office of Baker Botts and a former IRS trial attorney, said one early employee at an artificial intelligence company expects roughly $300 million in shares to vest this year and fears the payout could push him into billionaire-tax territory.

Feldhammer said he and the client are exploring whether some of the employee’s unvested shares could be donated to charity before they are received.

Some founders are even delaying fundraising rounds that could increase the valuation of their companies and, in turn, inflate their personal net worth.

Advisers are also looking at restructuring assets. One strategy involves moving real estate out of limited liability companies and into revocable trusts or directly into owners’ names because such properties are already subject to property taxes and may not count toward taxable net worth under the proposal.

Others are considering buying pricey assets outside California — including artwork, yachts or vacation homes — and keeping them there.

Still, experts caution that there are limits.

The list of available tax-planning options is “relatively narrow” and is most useful for wealthy individuals hovering near the threshold where the tax begins to apply, according to wealth advisers.

And the legislation includes an anti-avoidance provision requiring transactions to have a legitimate economic purpose beyond simply reducing taxes.

“I like to tell my students this maxim of tax-planning: Pigs get fed, hogs get slaughtered,” said David Gamage, a law professor at the University of Missouri who helped draft the proposal. “You can often get away with some amount of restructuring affairs, but if you go too far and get too greedy, you can get in trouble.”

Supporters of the measure, backed by the healthcare union Service Employees International Union-United Healthcare Workers West, say the tax could generate as much as $100 billion to help offset federal healthcare cuts.

Critics argue it would further damage California’s reputation as one of the nation’s most expensive places for high earners.

“It’s offensive that when so many people are struggling to afford gas, groceries and life’s necessities, there’s a group of billionaires who are fixated on avoiding paying their fair share,” said Debru Carthan, a radiologic technician and union executive.

Some clients, meanwhile, have responded to the proposal with gallows humor.

According to adviser Jennifer Kowal of IEQ Capital, a few wealthy couples have even joked about ending their marriages, since the assets of spouses are counted together when calculating an individual’s net worth under the proposal.