What takes shape over the 96-page document isn’t really a scaled-up Medicare program, but something new altogether. As currently constructed, Medicare actually contains quite a bit of cost-sharing—particularly for prescription drugs—and an entire industry of private plans exist to beef up Medicare coverage and provide additional services for seniors. Sanders’s plan would more accurately be described as The U.K.’s NHS on steroids—a entirely government-backed endeavor bounded only by the limits of the delivery system and of the tax base that pays for it all.

But that last point is crucial. Especially in a system with no artificial or individual limits on how people can use their health insurance, the funding structure is absolutely vital to understanding how the system as a whole will respond to the health-care choices of over 300 million people. And beyond the “how will they pay for it?” criticisms from both Republicans and Democratic holdouts, for all American health-care reforms—especially one this massive—questions of redistribution, the minutiae of tax policy, and how those economic factors shape and alter behaviors and health-care choices are important. In fact, those questions are as important in understanding if the policy actually meets the goals of covering people and containing costs as the specifications of Medicare benefits. And the Sanders plan, as of yet, answers none of those questions.

The decision not to include a funding scheme was a calculated one, and as Sanders himself told the Washington Post, “there has not been the kind of research and study that we need” to put together cost estimates and funding plans in the proposed bill. Still, the landscape of ideas isn’t completely barren, as the Sanders camp also released a six-page white paper Tuesday outlining some ways that the country could pay for Medicare for All. Unsurprisingly, the list of suggestions includes some pretty Sanders-standard stuff, including heavy wealth taxes and an increasingly progressive tax system. The two suggestions most directly related to how health insurance is funded now are a 7.5 percent payroll tax on employers and a 4 percent income tax for families above poverty.

While that document was not intended to provide a singular roadmap to paying for Medicare for All, it’s worth noting that the document contains at its most optimistic about $1.6 trillion per year in combined revenues between suggestions. That means that if Sanders gets everything on his tax wish list—including raising the marginal income tax by something like 15 percentage points on the richest quintile of Americans—the revenues still come up to be about half of the $3.4 trillion the country spends annually on health care, or about $5,000 of the over $10,000 in care spent per capita.

Even if his plan saves half a trillion or more per year in administrative costs under a unified program, there’s a pretty big gap between here and there. This is all math with the kind of rigor that might not even qualify for “back of the envelope” status, but the clear call is that the Sanders plan will have to do some novel things to create revenues or dramatically cut the cost of care in order to work.