The MTA desperately needs to fix the crumbling subway system—this is an undisputed fact. But what’s less clear is how, exactly, the major players behind the transit system plan to get the necessary funding for major fixes.

Though Governor Andrew Cuomo recently unveiled an $836 million action plan—which includes both long- and short-term solutions for bringing the system to a state of good repair—it doesn’t take into account funding beyond the current state of emergency. And while Mayor Bill de Blasio has proposed a “millionaire’s tax” (which would increase the income tax rate for individuals making more than $500,000, and couples making more than $1 million) as a means of generating transit funding, it has yet to gain steam.

One proposition that’s begun to generate chatter—and even has Cuomo’s support—is “value capture,” or taxing building owners whose properties increase in value as a result of being near transit. The New York Times uses the Second Avenue subway as an example:

Proponents point to the Upper East Side of Manhattan, where co-op and condominium prices in a 10-block stretch near the Second Avenue subway have risen 6 percent since it opened in January 2017, according to figures from the Corcoran Group, a large real estate firm. In Manhattan’s main business corridors, from 60th Street south, the benefit of being near a subway adds $3.85 per square foot to the value of commercial property, according to calculations by two New York University engineers.

A preliminary plan from the state (which, as a reminder, controls the MTA) calls for creating special districts near new transit projects—but only ones costing $100 million or more—with building owners within those districts having their property taxes adjusted accordingly. (This means projects like East Side Access or the second phase of the Second Avenue subway would qualify.)

As the Times notes, the proposal “calls for before and after assessments in neighborhoods where a new transportation project, like the extension of a subway line, raises property values. Officials would determine the difference between the previous assessment and the new, higher one. Of the tax on that difference, 75 percent would go to the transit agency and 25 percent to the city.”

Naturally, the bill has its supporters—the Regional Plan Association, for one, says it’s an “innovative financing mechanism”—and its detractors, which include the Real Estate Board of New York, and City Hall. “This is not the way to address the problems of the M.T.A.,” the first deputy mayor, Dean Fuleihan, told the Times. (This despite the fact that the city had initially proposed using value capture as a way of funding its proposed Brooklyn-Queens streetcar system, which has yet to make significant progress.)

Implementing any kind of value capture plan would take some time—it would also need the approval of the state legislature—but it has worked in other cities, including Hong Kong.