One could easily imagine this idea being proposed in Seattle, so it's worth checking out the fine print:
A series of tax breaks given to tech companies to ensure that they stay in San Francisco seems to be benefiting both start-ups and the city, if even just a little.
The tax break, called a “community benefit agreement,” makes it possible for companies housed in specific low-income areas of San Francisco to receive breaks on some of the city’s payroll taxes, but to do so, they must perform a number of tasks that help improve their neighborhoods.
Okay. But, then we meet a company called Zendesk, valued at $1.5 billion, whose wealthy employees are served meals by homeless people who inhabit the low-income area the company has picked for its offices. The total value of the tax breaks that Zendesk and 14 other companies got in one year as a result of locating in low-income San Francisco neighborhoods: $1,903,321.
The amount that Zendesk spent in 2013 to pay the homeless people feeding its employees: $3,500.
Even if you take Zendesk's total spending in 2013 on "donations and hiring local businesses"—according to this New York Times story, $100,000—and then assume the 14 other companies, on average, spent a similar amount, you end up with local government losing about $400,000 in tax revenue.
This is a complicated project, with hard-to-calculate benefits like volunteer hours and redevelopment involved. But, if Seattle were to go down a road like this, it would be wise to make sure the city benefits as much as the tech companies.