The sun was rising and the coffee flowing as billionaire developer Richard LeFrak welcomed guests to his Hamptons home last August for one of the season’s more unusual gatherings: a “salon discussion” about a new tax break.

The star of the exclusive event was Treasury Secretary Steven Mnuchin, there to explain a key piece of President Donald Trump’s signature tax overhaul. Investors developing real estate or funding businesses in some 8,700 struggling communities designated as “opportunity zones” would get big breaks to boost their returns. The administration expected the incentives to pump $100 billion into long-overlooked parts of the country.