Twitter, along with other tech companies in San Francisco, may receive local tax breaks for agreeing to give "charitable contributions" that in Twitter's case includes giving away promoted tweets to local organizations and volunteering.

According to documents from San Francisco's government website, the tax deal—which requires companies with over $1 million in payroll expenses to negotiate a Community Benefits Agreement with the city— exempts approved companies located in the North of Market/Tenderloin Community in the city from the local 1.5 percent payroll tax on employees that are hired once the company moves into the neighborhood.

As first reported on Buzzfeed, tech companies including Twitter, Microsoft-owned Yammer and ZenDesk have agreed in their contracts to a list of requirements that include things like supporting local businesses, supporting workforce development and establishing local nonprofit grants programs.