SENATORS HAVE been on a roller-coaster ride since the House bill to replace most residential property taxes with a higher sales tax landed in their laps nearly a month-and-a-half ago.

First they wouldn’t go as far as the House did, since that put the state in the inappropriate position of funding city and county government, and not just schools.

Then they would go farther, eliminating school taxes not just on homes, but also on cars and businesses.

Then, a subcommittee reviewing ways to do that decided it simply wasn’t possible.

Last week, it looked as though the panel would settle on a plan to eliminate school taxes on the first $200,000 of homes’ value and limit the portion of their income that homeowners would pay in property taxes.

Finally, the panel agreed Thursday to eliminate most of the taxes that pay to run county government, and leave school taxes alone.

If all of this makes you a bit dizzy, it might help to return to basic principles.

There are three legitimate reasons for legislators to swap a higher sales tax for lower property taxes:

• To help those people whose property values have outstripped their incomes, creating a genuine burden.

• To change the way we fund schools so spending is based on how much it costs to educate each child rather than how close that child lives to valuable property.

• As part of a comprehensive overhaul of the state and local tax system.

The House plan kills the first gnat with a sledgehammer, helping that small portion of people who are unduly burdened by property taxes by nearly wiping out the burden on every homeowner.

Fortunately, senators have found a way to solve the actual problem, at about a tenth of the cost, by creating a circuit breaker that guarantees that homeowners will not have to spend more than 5 percent of their income on property taxes. That idea, projected to cost $100 million a year, is reasonable.

The same cannot be said for the rest of the plan.

Like the House, the Senate now proposes to make people with frugal county governments subsidize folks whose counties spend lavishly. (This will lead those in frugal counties to demand spending limits in big-spending counties, which the House and Senate already want to do.) That does not do a single thing that the state of South Carolina needs to accomplish.

Nor does the Senate plan even pretend to reform the tax system. Instead, the elimination of most county property taxes is yet another in a long line of stopgap measures that will cause more problems than it solves.

On Tuesday, this slimmed-down package goes before the full Senate Finance Committee, where senators have the opportunity to design a truly comprehensive tax reform package that eliminates the undue burden property taxes place on some people, and disconnects school quality from community wealth.

If senators can’t do that, they should strip out the county tax break and approve a bare-bones bill that increases the sales tax by a fraction of a penny to create an income-based circuit breaker. The subcommittee’s current plan is simply not acceptable.