Salesforce, led by dynamic cofounder and co-CEO Marc Benioff, aims to establish itself as the corporate citizen in San Francisco. Now the city’s biggest private employer–and tenant of its tallest skyscraper–has just thrown its weight behind solving a problem that tech giants like Salesforce get blamed for: gentrification that’s pushing poor and middle-class residents out of their homes and into the streets or suburbs.

Today Benioff and Salesforce announced moral and monetary support for Proposition C, the November city ballot initiative that aims to raise $300 million per year for housing subsidies and homeless services. Prop C would more than double San Francisco’s

housing-assistance spending by levying an average tax of 0.5% on business gross receipts over $50 million per year.

Related: Across Silicon Valley, cities may tax big tech to help struggling renters

San Francisco’s Chamber of Commerce is staunchly opposed to the measure, and opponents have raised a reported $100,000 to campaign to defeat it. (London Breed, the city’s new Mayor, also opposes Prop C.)

Prop C opponents are battling not only local activists and nonprofits, but a megacorporation. Along with the extra taxes it would pay, Salesforce is putting even more money behind Prop C. The San Francisco Chronicle reports that Salesforce and Benioff will each donate $500,000 to the campaign for the measure. Benioff will spend an additional $1 million on his own advertising campaign for Prop C.

The news marks Salesforce and Benioff’s biggest foray into politics, but it is far from his first involvement in civic matters. The billionaire philanthropist and his wife Lynne contributed about $250 million to what became the UCSF Benioff Children’s Hospital in San Francisco. The company spent $110 million on naming rights to the new $2.2 billion Salesforce Transit Center.

However, San Francisco’s version of the Port Authority bus terminal closed on September 25, about six weeks after its christening, when workers discovered broken beams. (Officials aim to reopen the center at the end of the week.) Salesforce undoubtedly hopes that anything else it helps build in the city will fare better.