A proposed San Francisco ballot measure could fast-track approvals of 6M SF of office in Central SoMa, but there is a catch. New office projects would have to contribute to affordable housing projects or pay additional fees, the San Francisco Business Times reports.

Under the proposed measure, the area would not fall under Prop M, which caps new office space in the city at 950K SF each year. Office projects would have to add to affordable housing either by dedicating land, buying existing affordable housing or pay an affordable housing fee within 30 days of approval or a 25% larger fee for affordable housing.

The ballot measure is being submitted by TODCO Executive Director John Elberling in partnership with SPUR as a way to promote more affordable housing.

San Francisco is expected to reach its office allocation with several large office projects expected to deliver in 2018 and 2019 that could eat up the current allocation of about 2M SF. Some have cautioned Prop M could end up slowing down new development in Central SoMa and beyond.

Central SoMa has long been touted as the next bastion for new development and redevelopment, and the plan will increase building heights, add affordable housing and allow for densification. The Central SoMa plan is expected to be approved in spring 2018.

Under the proposed ballot measure, any offices beyond the 6M SF reserve would be denied for 15 years or until 15,000 new housing units are built, approved or converted. The reserve also would be deducted from the Prop M allocations for 10 years, meaning Prop M’s allocations for the rest of the city would be reduced to 350K SF annually during that time.

In 2016, voters passed Prop O, which exempted the 5M SF of office at Fivepoint’s Shipyard and Candlestick Point projects from Prop M allocations.