OUR STATE’S PRACTICE of making small businesses pay higher income taxes than larger businesses fits neatly in the same category as our sales tax on food, our cap on automobile sales taxes and our practice of charging higher taxes on rental housing than on owner-occupied property: They all cry out for change.

So we’re delighted that the Senate is focusing on the problem of charging home-grown businesses — the ones that provide the bulk of our jobs — a tax rate that’s 40 percent higher than the rate large corporations pay. Eliminating that disparity very well might spur job growth, and it certainly would make the tax system fairer.

We’re equally delighted that senators seem poised to reject Gov. Mark Sanford’s plan to lower the income tax rate for everyone. The fact is that neither our general tax burden nor our income tax burden is particularly high compared to other states. Although our 7 percent income tax rate is among the nation’s highest, all of our exemptions and deductions lower the effective rate — the rate people actually pay — to the middle of the pack, and near the bottom under some scenarios.

But while there’s a stronger argument for lowering the tax rate on small businesses than for lowering it on individuals, and while it would do less harm to our ability to pay for basic services, the business tax cut has the same fundamental flaws as the governor’s plan.

The most immediate problem is that it would reduce the amount of tax money the state collects at a time when the state is not collecting enough money to adequately fund essential services.

A slowly improving economy is allowing us to start catching up on some of those services next year. But we still won’t have enough guards in our prisons — let alone the educational, job-training and addiction-treatment programs that could turn the prisoners we let out into better citizens instead of better criminals. We still won’t be providing services for all of our elderly and disabled neighbors who can’t afford the long-term care they need. We still won’t be giving every child the opportunity to get a good education. And on and on.

Mr. Sanford says we’d have plenty of money for essential services if legislators would adopt his cuts and cost-saving measures — many of which we wholeheartedly support. But the Legislature has made it clear that it will not adopt those proposals, and as long as that’s the case, we can’t pay for essential services.

Even if we had more money than we needed to run the government, though, there would still be a problem with both the governor’s tax cut and the Senate tax cut: Both are being proposed in a vacuum, without considering the effect they have on our overall tax system.

The Senate tax cut wouldn’t merely equalize the tax rate paid by large and small businesses; it also would reduce the portion of government services that are funded by businesses — and increase the portion paid for by individuals. We might well want to do that, but it’s hard to say, because that shift isn’t part of the debate. And that’s just the obvious shift this tax cut would produce; there are no doubt other, less obvious, ones.

One of the biggest reasons we have so many inequities in our tax system is that we keep making these piecemeal changes. That’s got to stop. There are serious, well-thought-out proposals in the Legislature to actually reform our tax system — to increase some taxes while reducing others, to change the rules for who pays which taxes. A plan to treat small and large businesses alike would fit nicely into one of those proposals, and it should. It should not, however, be passed by itself.