'Million Dollar Listing' Star Josh Altman L.A.'s Mansion Tax 'Dumbest Tax Ever' ... Everyone's Gonna Feel It

L.A.'s new "mansion tax" is about to go into effect, forcing sellers to cough up a ton of cash if their property sells for at least $5 million ... and Josh Altman is one of many real estate agents who think it's absurd.

Josh joined us Thursday on "TMZ Live," and immediately dumped on measure ULA ... calling it "the dumbest tax ever put through in the history of Los Angeles." Passed on the ballot last November, it slaps a 4 percent tax on homes selling for $5 mil and up, and 5.5 percent on those selling above $10M.

Josh points out the ridiculous ways agents would have to work around the taxes if they wanted to, including listing it for cheaper than its actual value ... just to dodge the additional tax.

The selling point to voters who supported the tax was the funds would go toward battling the homeless crisis in L.A. by developing more affordable housing -- it's projected to bring in $1B annually.

Josh tells us he's all for helping the unhoused, but just doesn't believe they'll get a dime from the new taxes.

The "mansion tax" goes into effect April 1, so sellers are scrambling to close deals before that -- and while many think this only impacts the rich ... Josh told us why he believes there's gonna be a trickle-down that eventually hurts all homeowners.

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