In an op-ed for Vox, billionaire businessman and former mayor Michael Bloomberg presented the details of a plan to make in-state college tuition free for students from low-income families.

Using money from an existing tax credit, Bloomberg envisions a system in which any student who meets certain test score thresholds gets full tuition for the next four years. After that, students would be eligible for loans to make their costs comparable to community college. The cap would be $50,000 per year for students earning less than $50,000, and the maximum for the top quartile would be $75,000.

Some details, of course, are far from finished: Bloomberg has not said where the money would come from to cover the loans or how much it would cost.

The country’s existing public-college enrollment system has long riled pro-education advocates, who argue that debt-laden students are steered away from top-tier universities by financial aid policies that prioritize low-income families and do not provide the same opportunity for financial assistance at in-state institutions.

U.S. News and World Report, which has tried several times to alter its formula, keeps a list of schools receiving the greatest levels of funding for in-state students, but they do not include taxpayer-supported schools whose tuition is covered by government money. (NYU, Carnegie Mellon, Brandeis and MIT all have status as public universities that does not exempt them from paying the same tuition as in-state residents.)

This in-state tuition cap would eventually take effect in a number of states, including Colorado, Delaware, Illinois, New York, Rhode Island, Texas and Wisconsin. The proposal has previously been called “dumbed down” by U.S. News and other sources.

U.S. News told Vox that it would not be affected by the proposal.

Read the full op-ed here.