COLUMBIA - A Senate subcommittee studying property tax relief adopted a loose working proposal Tuesday that features doubling the existing $100,000 home-value exemption for school operating costs.

The plan is very much in flux, with members saying they still hope to find the $2.4 billion it would take to relieve all classes of property of school operating taxes.

It will cost $144.2 million to increase the home exemption to $200,000.

The panel is studying a House-passed plan that raises sales taxes 2 cents and uses the 7-cent tax to pay most city, county and school taxes for owner-occupied homes.

Members tossed out the notion of replacing city and county taxes but want to relieve school taxes for all property if they can find the money.

Subcommittee Chairman Wes Hayes, R-Rock Hill, proposed a plan as a starting point, while members look for ways to fund the larger tax-relief program.

Hayes' proposal also includes income-based tax relief. Anyone who has less than $25,000 income would have property taxes capped at 5 percent of their income.

The working plan also includes a poverty index and removing the sales tax from food.

The $2.4 billion would require a 4 cent sales tax increase and the panel agreed that would not have a chance of passage.

The panel also heard some new figures from the Senate staff and state economists. One, for example, showed that people with incomes under $10,000 and houses valued at under $10,000 pay a total of $508,000 in property taxes. So it would cost about that much to exempt people at that income level, said Chief Economist Bill Gillespie.

Economist Gordon Shuford said those with houses valued more than $1 million and with incomes more than $100,000 pay $71 million in property taxes. The bulk of the $976 million in property taxes are paid by people in the middle range, Shuford said.

A Senate staff report said South Carolina is tied for 44th in the country as a percent of taxes paid compared with total income, at 9 percent. North Carolina is at 9.7 percent and Georgia is at 10 percent.

Another staff report showed that sales tax has fallen behind growth in population and inflation many times in the recent past, which would make it shaky for use to replace property tax.

"I do think that's a very serious issue," said Sen. Scott Richardson, R-Hilton Head Island. He said the state would have to keep a reserve fund to cover the years when the sales tax did not cover the needed amount.

The subcommittee will meet again Tuesday, with members told to come with other proposals if they have them. If not, they will proceed with Hayes' plan or the one the Senate tentatively adopted last fall that raises the sales tax 2 cents to pay school operating costs.