MOST ECONOMISTS and policy experts agree that there are a few basics to designing a good tax system. While we might disagree on precisely how our favored system measures up, most people would probably agree on these basics. An ideal system is built around:

• Adequacy. It brings in enough money to pay for whatever size of government the public desires. Stability and growth are both factors in this.

• Equity, or fairness. It is generally based on ability to pay.

• Efficiency, which to economists refers to its effect on actions. Either it encourages positive activity (home ownership, investment) or else it has no effect, good or bad.

• Low compliance cost. It doesn’t cost the state a lot to administer and collect, and it’s easy for the public to comply with.

“These often point in different directions, so there is a significant role for judgment regarding the best system,” William Fox, director of the University of Tennessee’s Center for Business and Economic Research and a leading national expert on state tax policy, told the state’s joint tax study committee this summer.

Most economists consider diversity, or balance, the key to dealing with that challenge.

As Holley Hewitt Ulbrich and Ada Louise Steirer write in “Paying for Government in South Carolina — A Citizen’s Guide”: “When we look at various taxes, no tax fits all criteria of a perfect tax.... The positives of one tax, then, will need to balance the negatives of another to create a good revenue system.”

Dr. Fox suggests thinking of a tax system like a retirement portfolio. A smart investor wants a mix of volatile and stable securities, of growth and income stocks, of stocks and bonds.

In trying to achieve the perfect balance, economists suggest such obvious strategies as including taxes on income, spending and wealth (property taxes). They say individual taxes should cover as many people as possible at the lowest possible rate. And many argue that, to the extent possible, a tax system should rely on taxes the public prefers to pay.

• How S.C. rates (This article contains several news items)

In South Carolina, about 70 percent of the money we collect to run state and local government comes from the property tax, the sales tax and the income tax. Most economists like this mix, because these Big Three taxes tend to balance each other.

The property tax is extremely stable; it brings in a predictable amount of money even when the economy lags. But it doesn’t grow very fast, it has a high compliance cost, and it scores low on efficiency, because it can push businesses away from some areas.

The sales tax has a low compliance cost and is usually considered a high-growth tax, but it’s regressive. That’s particularly true in South Carolina, because we tax food, which eats up a large share of the income of poor people, and we don’t tax most services, which tend to eat up a larger share of the income of wealthier people.

Many consider the income tax fair, and it grows well in a strong economy. But it doesn’t do well when the economy tanks, and the compliance cost can be high.

The state uses higher taxes on the sales of such things as gasoline, cigarettes, alcohol and hotel rooms, along with fees, to further balance the system or, as Dr. Ulbrich and Ms. Steirer write, to “offset some of the weaknesses of the income, sales and property taxes.” Taxes aimed at tourists can make sure they help pay for government services they use, for example, while gasoline taxes can make sure those who use the roads the most pay a larger share of building and maintaining them.

Dr. Fox likes our low sales tax rate. He also likes that we rely less heavily than most states on taxes on corporate income, which he believes discourage job growth.

But he gives us low marks for a high individual income tax rate and for relying on the sales tax more heavily than most states. He believes that’s one reason our income isn’t growing well with the economy: Economists consider the sales tax one of the biggest problems for the future, because as more consumer spending goes to services rather than sales, and as people make more Internet purchases, it taps a smaller percentage of total spending.

You can jiggle each tax to improve the mix. The state has made the homeowner property tax more progressive by reducing taxes on houses valued at $100,000 or less. On the other hand, while a progressive income tax can balance the regressive sales tax, we’ve made our income tax practically flat, so it doesn’t serve as a counter-balance.

• Grading Quinn-Sheheen (This article contains several news items)

My colleagues and I will be looking in greater depth at these criteria in the coming weeks, as we evaluate the various proposals for overhauling our tax system. But a useful starting place is to look at how their plans stack up against the ideal system.

The plan by Reps. Rick Quinn and Vincent Sheheen, because it’s so complex, gets mixed results:

• Compliance cost. It makes the tax system simpler and less expensive to administer and comply with, by trading property taxes for sales taxes. That’s a plus.

• Adequacy. It trades the stable property tax for the more volatile but faster-growing sales tax. So it should generate more money over the long term, but the annual growth would be less predictable, increasing the chance of service cuts or tax increases. But since the sales tax base is eroding, it won’t remain adequate without change. Quinn-Sheheen eliminates many sales tax exemptions, slowing that erosion. The plan may not be adequate, but that’s unclear.

• Fairness. Like the question of adequacy, this one is not clear cut.

On the negative side, the sales tax is regressive, and this plan raises it. Some exemptions it eliminates, such as gasoline and residential electricity, could make the sales tax more regressive. It eliminates the automobile property tax, which may be nearly flat.

But it makes our income tax slightly progressive. It exempts groceries from the additional 2 percent tax, making that less regressive. It reduces the most regressive sales tax exemption — the one on automobile purchases. It also phases out the local sales tax some counties collect for infrastructure and encourages counties to eliminate the local option sales tax, reducing reliance on the regressive sales tax in favor of slightly higher property taxes.

But are property taxes regressive, flat or progressive? For homeowners, they could be considered progressive thanks to that $100,000 tax break. But that doesn’t apply to rental property, which also is taxed at a higher rate. If landlords lower rent when their property taxes drop, this could make the tax system less regressive; if they don’t, it won’t.

• Efficiency. The property tax is very inefficient; i.e., it has a huge effect on spending decisions by individuals and businesses, and the effect is often negative. The sales tax also affects spending decisions if it gets too high, but it’s unclear exactly where “too high” kicks in. The plan probably scores fairly well on this criterion.

• Political support. It trades a tax the public hates for one most people prefer to pay. That’s a plus.

• Balance. This is a huge negative: It greatly reduces our reliance on the property tax and greatly increases our reliance on the sales tax, thus taking us from a fairly balanced system to one in which our state sinks or swims on the basis of consumer spending.

• The other plans (This article contains several news items)

The plan by a group of school finance officers mirrors Quinn-Sheheen on revenue raising but merely reduces, rather than eliminating, property taxes. That means it doesn’t change compliance costs. It scores well on adequacy and doesn’t do as badly on balance. It improves efficiency and might generate public support, although not as much on either measure. It is about as fair as Quinn-Sheheen.

Sen. David Thomas’ plan to increase the sales tax and eliminate all homeowner property taxes scores well on compliance costs, public support and efficiency. But it doesn’t do well on adequacy, balance or fairness.

Gov. Mark Sanford wants to reduce income tax rates and raise taxes on cigarettes and lottery tickets. That gets high marks for efficiency, because lower income tax rates could encourage economic development, while higher cigarette taxes should reduce smoking. Fairness is more subjective: Although trading a flat income tax for regressive taxes would usually be unfair, cigarettes and lottery tickets are discretionary items, so people can avoid higher taxes if they want to.

House Ways and Means Chairman Bobby Harrell’s plan to increase the sales tax to 6 percent on everything except food and hotels, eliminate a few small tax exemptions and do away with automobile property taxes would do a great deal to increase public support of the tax system, since people hate the car tax and like the sales tax.

Overall, though, both Mr. Harrell and, to a greater degree, Mr. Sanford are so limited in their changes to the current tax code that they would do little to improve, or harm, our tax system.

And that has been the problem with all of the tax plans lawmakers have considered, and passed, in recent decades: They have been targeted to achieve this goal or that, with little regard for how they affect the overall tax system. While any one change has little effect, the accumulation of tax change upon tax change creates a system that is far from the ideal, sometimes in ways we don’t even realize until we examine the alternatives.

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