COLUMBIA, S.C. - Giving tax breaks for paying private school tuition would cost South Carolina as much as $231 million in revenue in five years if legislation now in the Statehouse becomes law, according to a study released Tuesday by economists.

The fiscal impact study on the Put Parents in Charge Act from the state Board of Economic Advisors dampened arguments from school choice supporters that the bill would save the state millions of dollars and caused concern among some legislators who support the bill.

"Unless we can see on the other side where there's going to be a savings, that's going to be a problem," Rep. Shirley Hinson, R-Goose Creek, said. Hinson, one of the bill's co-sponsors, said she was waiting on a rebuttal to some of the study's findings from Gov. Mark Sanford's office.

The study showed the tax credits would cost the state's general revenue $29 million for the 2006-07 fiscal year. The bill would cost $231 million at the end of five years when it is fully implemented.

The study also showed modest savings of nearly $10.6 million at the state level, but found local communities would have to find a way to make up the difference.

"That translates into a tax increase," said Hinson, whose subcommittee passed the bill last week. "And that translates into a no, pretty simply."

The average tax credit for parents would be $1,462 per student or less. It could be as little as $806 for parents with less income, according to the study.

The study was requested by the House Ways and Means Committee members, who wanted estimates on how the Put Parents in Charge Act would affect state revenues. The full committee plans to take up the bill next week. The legislation would allow parents to claim tax credits for paying tuition and other costs for private schools, home schooling or public schools.

The Board of Economic Advisors' study contradicted a report by Clemson University economist Cotton Lindsey, who found that the state would save hundreds of millions of dollars the first year the bill was implemented.

"It truly supports and underscores what we've been saying about potential impact," said Scott Price, a lobbyist with the South Carolina School Boards Association. Price's group and the South Carolina Association of School Administrators paid for a study that showed the bill would cost public schools hundreds of millions of dollars.

That study was written by Harry Miley, a former economic adviser to former Republican Govs. Carroll Campbell and David Beasley.

The Board of Economic Advisors are the state's chief financial consultants and continually review tax and other revenue collections as well as estimating the fiscal impact of all legislation.

The board's study did find that per-pupil spending would increase if the bill is implemented.

"We find that to be a good thing in itself," said Sanford's spokesman Will Folks, who said the office had only reviewed the highlights of the study. "Obviously, we'll be taking a close look at it."

The study estimated that tax credits would be claimed for more than 12,000 students. Most of those students would be home-schooled children and those entering private schools, not students transferring from public schools.

The study also found that wealthier parents would benefit most from the tax credits. A family of four with two children would have to make about $35,000 in taxable income - about $55,000 in gross income - to benefit from the tax credit, according to the study.

About a fifth of public school students' parents fall into that range, according to the study. The vast majority - more than three-fifths - make less than that.