The Tax Cuts and Jobs Act, passed last month, amounts to a vast cutback in the construction of low-income housing. Because the tax rate for corporations has been lowered, the value of the credits is also lower. "It's the greatest shock to the affordable-housing system since the Great Recession," said Michael Novogradic, managing partner of Novogradic & Company, a national accounting firm based in San Francisco. According to an analysis by his firm, the new tax law will reduce the growth of subsidized affordable housing by 235,000 units over the next decade, compounding an existing shortage.