MARYLAND GOV. Martin O’Malley (D) has been a prolific tax-raiser, having advocated or acceded to some 40 new or increased levies since taking office almost seven years ago. Those tax hikes have generated almost $10 billion, according to one conservative group’s estimate, which the governor has not tried to refute. They have helped pay for generous spending on public schools, higher education and the state’s transportation network and social programs.

Little surprise, perhaps, that in the race to succeed Mr. O’Malley, the pendulum has swung back toward tax cuts. In the context of an improving economy, that’s for the good; no doubt, plenty of Marylanders would appreciate keeping a greater share of their income. But candidates have an obligation to explain how they intend to offset any loss of revenue, especially since several of them also propose new spending.

Del. Heather R. Mizeur, the most liberal of the three Democratic contestants, has floated a soak-the-rich plan while simultaneously promising to cut personal income taxes for 90 percent of Maryland taxpayers. It’s not clear whether the math would work, but her program would do nothing to help the state’s already tepid climate for business. She also proposes huge spending on education, transportation and much else, with highly speculative means (such as legalizing and taxing marijuana) to pay for it all.

Attorney General Douglas F. Gansler (D) would lavish tax breaks on an array of interest groups; he, too, is loath to say how they would be paid for. He proposes to slash the corporate income tax by more than 25 percent. He would raise the threshold for the inheritance tax to $5 million from $1 million to keep well-to-do retirees in the state.

As icing on this cake of goodies, he would excuse retired teachers, first-responders and military veterans — all “heroes,” in Mr. Gansler’s estimation — from paying taxes on part of their pension income. How much this package of panders would cost in the short to medium term is not clear. Another rival for the Democratic nomination, Lt. Gov. Anthony G. Brown, estimates that the corporate tax cut alone would leave the state with a budget hole of some $1.6 billion — the equivalent of about one-tenth of general fund revenue this fiscal year.

Mr. Brown seems slightly less interested in pushing the fiscal pendulum, perhaps because, as Mr. O’Malley’s No. 2, he backs the policies of the incumbent administration. But Mr. Brown hasn’t resisted the urge completely; he would extend a modest tax break to veterans at a cost (including some new programs) he pegs at $24 million in his first term.

Republican candidates are pressing for a variety of tax cuts, also without specifying how they would be paid for.

In an improving economy, there are good reasons to consider targeted tax cuts — first and foremost, to strengthen Maryland’s ability to maintain a robust private sector in an era of straitened federal spending. Candidates who want their proposals to be taken seriously should fill in the policy blanks.