Sen. Bernie Sanders has proposed paying for his policies that transform large sectors of the government and the economy mainly through increased taxes on wealthy Americans. A pair of new studies published Monday suggests Sanders would not come up with enough money using this approach, and that the poor and the middle class would have to pay more than Sanders has projected in order to fund his ideas.

The studies, published jointly by the nonpartisan Tax Policy Center and the Urban Institute in Washington, concludes that Sanders’s plans are short a total of more than $18 trillion over a decade. His programs would cost the federal government about $33 trillion over that period, almost all of which would go toward Sanders’s proposed system of national health insurance. Yet the Democratic presidential candidate has put forward just $15 trillion in new taxes, the authors concluded.