NO RATIONAL person could accuse Gov. Mark Sanford of being a proponent of higher taxes. Some would even point to his single-minded focus on cutting income taxes in the face of crippling budget cuts at vital state agencies as proof that he opposes even an adequate level of taxation.

But just to make sure there was no question, the governor went out of his way recently to remind voters of his opposition to taxes. He noted that in addition to his crusade as governor, “When I was in Congress my voting record was rated number one by the National Taxpayers’ Union in votes to limit taxes.”

“Limiting government and its tax load drives my political philosophy...,” he wrote to state legislators.

And yet there was our anti-tax crusader, vetoing a bill that would have slashed property taxes for the people who are experiencing the most burdensome increases. The main reason Mr. Sanford gave for his veto was his belief that the Legislature violated the constitution when it passed the bill. But he made it clear that he was equally concerned about the “unintended consequences” the bill would have on everybody else’s taxes.

That’s the reason that my colleagues and I have been giving for, oh, a decade or so now for why the Legislature needs to quit making piecemeal changes to tax policy — be they tax increases or, as is almost always the case, tax cuts: Changing any part of the tax system inevitably results in changes to other parts of the tax system, but most legislators are blissfully oblivious to those inevitable changes.

It is a problem that legislators and others who are convinced that our taxes are too high have dismissed as a fig leaf behind which they claim we hide a lust for tax increases.

So are we now to conclude that Mr. Sanford has donned a fig leaf with which to conceal his own lust for tax increases? After all, he has heretofore shown little concern for the ripple effect that a single change — say, cutting top income tax rates — would have on the overall tax system.

Or should we conclude that the problems with this particular piecemeal change were so glaring that they could convert any thinking person into an advocate of comprehensive reform?

Here’s how Mr. Sanford described the Legislature’s approval of the bill to cap taxable increases in property values at 20 percent every five years: “This bill ... causes a shift in the distribution of state funding that may have been something the General Assembly considered, but at this point it appears to be an unintended consequence rather than an outcome derived by debate.”

The governor was being kind.

Local officials had warned that they would be forced to increase taxes on cars, businesses and houses whose values aren’t increasing quickly if they had to artificially cap taxes on rapidly appreciating properties. But legislators insisted that this couldn’t possibly happen.

They got away with that in some circles because no one had bothered to do an analysis of what the law would do. Once the state Chamber of Commerce hired economist Harry Miley to analyze actual tax assessments in the seven counties that had compiled reassessment figures last year, the problem became difficult to ignore: The new law would result in higher taxes for the majority of taxpayers — from 56 percent in Richland County to 82 percent in Florence County. Mr. Miley projected that statewide, such people would be taxed an average of $200 a year more on a $100,000 home in order to pay for tax breaks for high-end homeowners.

And there had been little if any discussion of the tax shift that Mr. Sanford objected to: one that would give extra state money to the handful of school districts where the cap affected the most properties and take money away from the rest of the districts.

About half the money the state spends on schools is distributed based in large part on the “index of taxpaying ability,” or the total value of taxable property in the district. The lower the value of taxable property, the more money the state provides per student, under the theory that those districts simply can’t afford to spend as much as is needed. The 20 percent cap lowers the amount of taxable property in a district. So wealthy districts look poorer than they are and receive more state money to help pay for good schools — which, of course, they can afford on their own.

There’s nothing unique or even unusual about a tax change having such dramatic, undebated and unanticipated consequences. It happens all the time. What’s unusual about this one is that a lobbying powerhouse — the state Chamber of Commerce — recognized that its members would be hurt, so it mounted a major effort to point out the problems and get the legislation rejected.

Mr. Sanford concluded his veto message by calling on lawmakers to join him in “a more comprehensive debate of tax reform to include both property tax relief and income tax relief.”

That’s a much better place to start a debate than at either tax alone. But a comprehensive debate also has to include the sales tax and the host of smaller taxes and fees levied by state and local governments. It’s only when you look at all of those items that you can consider how you are changing the federal tax burden on South Carolinians, tax collections that are earmarked for particular items, the portion of taxes paid by businesses vs. individuals, the wealthy vs. the poor, those who live in rural areas vs. those who live in urban areas, the young vs. the old and on and on. And it’s only when you consider all of those factors that you’re able to change tax law in a way that doesn’t lead to all sorts of unintended consequences.

Ms. Scoppe can be reached at cscoppe@thestate.com or at (803) 771-8571.