Unlike Rubio and Paul, Ted Cruz has not yet released a full tax plan, though he frequently talks about wanting to abolish the IRS. He has hinted at support for some type of flat tax, saying he supports a tax code “that lets every American fill out his or her taxes on a postcard.” However, Cruz’s flat tax may not be completely flat. He has indicated a willingness to continue some popular deductions such as the write‐​off for charitable contributions and the mortgage‐​interest deduction.

Likewise, most of the governors and former governors running for the nomination have offered only a general idea of what they intend to propose on taxes. But, unlike the senators who are running, the governors have a track record that can tell us quite a bit.

Perhaps the most detailed plan put forward by any of the governors belongs to Chris Christie. Christie has called for simplifying the income‐​tax system to just three individual rates, with the top rate no higher than 28 percent and the bottom rate in the single digits. He also calls for cutting the corporate tax rate to 25 percent. To ensure that the overall plan is revenue neutral, he would radically reduce deductions, credits, and targeted provisions in the tax code — on both the personal and the corporate side. One way to do this, he has indicated, might be by capping the total amount of deductions and credits that an individual or married couple could take. And, as one piece of the entitlement reforms that Christie has proposed, he would eliminate payroll taxes for those over 62 or under 21. As governor, Christie has generally been strong on taxes, signing substantial business‐​tax cuts in 2011 and proposing a 10 per­cent across‐​the‐​board income‐​tax cut in 2012. He has repeatedly vetoed tax hikes on higher earn­ers passed by the Garden State’s Democratic‐​controlled legislature.

During his eight years as governor of Florida, Jeb Bush was generally considered much more aggressive on cutting taxes than he was on reducing spending. Cato’s biannual fiscal report card from 2006 stated: “Jeb Bush leaves office with a well‐​deserved reputation as one of the most aggressive tax cutting governors in the nation. He has proposed and signed into law a tax cut virtually every year of his tenure, ranging from cuts in property taxes to a phase‐​out of the intangibles tax.” As a presidential contender, Bush says that he is considering some type of flat tax and “bigger and broader tax relief.” However, it should be noted that he is the only Republican candidate who has not signed Grover Norquist’s pledge to the American people not to raise taxes.

While Bush had a fairly good tax record as governor, Mike Huckabee had a dreadful one. Huckabee received a D on Cato’s report card for his entire tenure and an F for his final term, principally because of “his insistence on raising taxes at almost every turn throughout his final term.” The report card gives Huckabee credit for pushing, in his first term, for a sweeping $70 million tax‐​cut package. That was the first broad‐​based tax cut in Arkansas in more than 20 years. He even signed a bill to cut the state’s 6 percent capital‐​gains tax — a significant pro‐​growth accomplishment. But nine days after being reelected in 2002, he proposed a sales‐​tax increase to cover a budget deficit caused partly by large spending increases that he had proposed or approved, including an expansion in Medicaid eligibility that he had made a centerpiece of his agenda in 1997, his first full year in office. He also went along with a 3 percent income‐​tax “surcharge” and a 25‐​cent increase in the cigarette tax pushed through by Democrats in the legislature. Huckabee is currently an advocate of the Fair Tax, a form of national retail sales tax, although he has been vague about the rate. Lower‐​income Americans would receive a “prebate” payment to offset their tax liability.

Scott Walker may have the best record on taxes among the governors running. He cut income‐​tax rates in both 2013 and 2014, in the process reducing Wisconsin’s five income‐​tax rates to four lower rates. Those cuts are expected to save Wisconsin taxpayers more than $500 million annually. That helped earn Walker a B on Cato’s scorecard, though his overall grade was held down by some weakness on spending. In the current campaign, Walker says he would “slash the marginal tax rates for everyone across the board — go to a simpler, more flat tax.”

As good as Walker’s record on taxes is, Rick Perry could give him a run for his money. As governor, Perry approved a business‐​tax overhaul that replaced Texas’s corporate fran­chise tax with a modified‐​gross‐​receipts tax called the “margin tax.” The added revenues were used to reduce local property taxes, but critics said that the overall effect of the package was to centralize gov­ernment power in Austin. Perry also signed bills providing more than $700 million annually in additional tax cuts, including an extension of a $1 million exemption for small business under the margin tax, a temporary cut to the margin‐​tax rate, and various sales‐​tax exemptions for business purchases. Like Walker, Perry earned a B on the Cato report card. Perry has not spelled out a tax plan for this campaign, but during his 2012 run he proposed a system whereby taxpayers could choose between the current tax system and a 20 percent flat rate, whichever was lower.

Finally, among those candidates without previous electoral experience, Ben Carson has been the most aggressive on taxes, calling for a flat tax of 10 to 15 percent. Carly Fiorina has only said that the current tax system is “in desperate need of reform.” She has called for a simpler code and tax cuts to spur innovation, but has provided no details.