How would San Francisco's proposed fees on empty storefronts affect retail and mixed-use properties?

NAI Northern California, NAI NorCal, Bay Area, Retail, Commercial Real Estate, CRE, San Francisco, SF
This week the San Francisco Board of Supervisors will vote on whether to require owners of vacant storefronts unoccupied for more than 30 days to register their properties and pay an annual fee. This is one of the proposals they are considering to get a better idea of and start to remedy the glut of unused storefront space around the city.
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