There is no doubt that an individual-income-tax code with many fewer deductions and credits — Cruz has suggested, for instance, keeping only the mortgage-interest deduction and an incentive for charitable giving — would be easier to enforce and therefore require fewer IRS agents. (A flat tax per se would not necessarily be easier to administer than a progressive one with many rates but few deductions and credits. Everyone can read tax tables.)

But tax experts say that, while the federal revenue agency could shrink under Cruz’s proposal, it could only get marginally smaller — not nearly small enough to say it’s been “abolished.” “You’d need slightly fewer revenue agents to conduct the same number of audits,” for instance, says Alan Viard, of the American Enterprise Institute. Donald Marron, a Bush-administration veteran and former head of the widely respected Tax Policy Center, says an idea like Cruz’s could make the IRS “smaller, sure. But vastly smaller? Probably not.”

That’s partly because the IRS does a lot of things besides just process complicated individual tax returns. Much of its resources, for instance, go into enforcing the corporate tax code, which Cruz’s campaign says he doesn’t have plans for yet.