SAN FRANCISCO — Maria Poblet, who leads an organization that assists Latino families facing eviction in San Francisco, says she appreciates the philanthropy that the city’s technology companies do in far-flung places to address global poverty and the environment. But what she really wants to see them do is pay more taxes to help with homelessness and lower-cost housing in San Francisco.

“You have a C.E.O. who cares about kids in Ghana one week or dolphins the next week. Those are important,” she said. “But the people impacted by displacement in San Francisco are a worthy cause, too.”

Ms. Poblet is part of a group of activists behind an initiative by three city legislators to impose a payroll tax that would apply only to technology companies, which have been the engine of a booming economy that now appears to be slowing.

Eric Mar, a member of the city’s Board of Supervisors, announced the proposal last week for a 1.5 percent payroll tax that would serve as a form of indemnification for what he described as the downside of the technology boom.