That would affect every state, of course, but a slowdown in affordable housing construction would be particularly brutal for California, which has a huge homeless problem and a $500,000 median home price that is more than twice the national level.

“Affordable housing” is a frequently misunderstood term. While many people use it as shorthand for anything that seems affordable on a typical salary in their area, it refers to subsidized units that are set aside for a city’s lower-income residents. Beyond cheap rent, these developments offer things like flu shots, job training and discounted internet that keep people employable and help them move up in the work force.

To build these units, nonprofit developers use a mix of bonds and tax credits that offset the cost of construction and allow them to offer lower rents for tenants. A little more than half of subsidized developments are financed with tax-free private activity bonds. They also get money from tax credits that developers transfer to corporations, which then use the credits to lower their taxes.

The House version of the bill eliminates private activity bonds, which would reduce the supply of new affordable housing by close to 1 million units, one-third of those in California, according to an analysis by Novogradac & Company, a national accounting firm based in San Francisco. It also reduces the value of investing in low-income housing tax credits.

The Senate version of the tax bill is less extreme: It leaves private activity bonds intact but reduces the value of low-income tax credits.