San Francisco's New Inclusionary Housing Rules Reshape Developer Calculus Across Mission, SoMa

San Francisco's Planning Department has quietly become ground zero for one of the Bay Area's most contentious housing policy experiments. New inclusionary housing rules that took effect in April 2026—requiring developers to dedicate 25 per cent of units to affordable housing in transit-rich zones—are already reshaping project economics from the Mission District to SoMa, with implications that extend far beyond spreadsheets.

The policy mandates that affordable units remain deed-restricted for 55 years, nearly double the previous 30-year requirement. For a typical 150-unit development in the Mission near BART's 24th Street station, that translates to roughly 37 affordable units locked in at below-market rates. Developers argue the extended timeline erodes project viability; affordable housing advocates counter that permanent affordability prevents displacement cycles that have hollowed out neighbourhoods for decades.

Early market data tells a nuanced story. Of 12 major projects submitted to Planning since April, only three have moved forward unchanged. Five have been redesigned to reduce overall unit counts—a strategy that proportionally increases affordable units while lowering total project costs. Four remain in limbo. Meanwhile, applications for projects in lower-density neighbourhoods like the Outer Sunset and Richmond have ticked upward, suggesting developers are hedging their bets by shifting focus to areas with looser requirements.

The Department of Housing and Community Development reports that the new rules will theoretically generate 2,100 additional affordable units over the next decade—a meaningful addition to a city that produced just 1,847 affordable units in 2024. But economists question whether the policy creates a secondary effect: constraining overall housing supply as marginal projects become uneconomical, potentially pushing prices higher for the existing stock.

The real test comes in established neighbourhoods undergoing transition. In the Mission, where median rents have climbed 34 per cent since 2020, the policy provides some protection against wholesale gentrification. A 200-unit Dolores Street project now includes 50 permanently affordable units under the new framework—a guarantee that wouldn't have existed under previous rules. That matters for a neighbourhood where longtime residents and small businesses have already retreated to Oakland and further east.

City planners are monitoring three metrics: the absolute number of affordable units delivered, the racial and economic diversity of neighbourhoods retaining affordability, and whether overall housing production stalls. The answer to that last question will determine whether San Francisco has found genuine policy balance or merely slowed the inevitable.

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