PROVIDENCE — Rhode Island taxpayers contributed $1.1 million to help renovate the Wrentham House, an 1891 mansion on Newport’s Ocean Avenue, now available through Christie’s Great Estates for $14.5 million.

And that doesn’t include the carriage house.

Taxpayers will contribute an estimated $2.7 million more for renovations to the 5,500-square-foot carriage house, which may be on the market for an additional $5 million.

The 1891 estate with 12 bedrooms, 15 bathrooms and breathtaking ocean views is among the many properties that qualified for Rhode Island’s historic structures tax-credit program, which offers property owners and developers breaks on income taxes worth 30 percent of qualified historic-renovation costs.

The program, largely credited as an economic-development tool responsible for revitalizing abandoned mill complexes across the state, also allows single-family houses, smaller condo developments and private social clubs to qualify for millions of dollars in reimbursements every year.

The exclusive Hope Club, in Providence, received tax credits worth $1.1 million for renovations in 2004; the Newport Country Club earned $1.8 million in 2005; and the private Clambake Club of Newport will receive an estimated $810,000 this year for ongoing historic upgrades.

The rules might be about to change.

A bill backed by House Majority Leader Gordon D. Fox, D-Providence, the sponsor of the original tax-credit law, would disqualify single-family houses, social clubs and properties that contain fewer than 10 residential units from the popular tax-credit program estimated to cost state taxpayers $66.1 million this year.

“Single-family homes and some of the smaller projects approved were not in my original intent,” Fox said yesterday before a public hearing on his proposal. “This was about making jobs, cleaning up old mill sites, creating a neighborhood tax base for local communities.”

Fox’s proposal, which is cosponsored by House Speaker William J. Murphy, D-W. Warwick, also reduces the reimbursement, from 30 percent of qualified rehabilitation costs to 22 percent, or 25 percent for developments that include commercial space.

Those who testified at yesterday’s packed House Finance Committee hearing generally supported the changes. But despite the backing of the House leadership, the fate of House Bill 8016 is far from certain.

Because Fox’s bill is not retroactive, it will not save any money in the current fiscal year. The legislation would apply only to current projects that have not incurred substantial construction costs, defined as 10 percent of the first phase of rehabilitation expenditures.

And Fox could not immediately quantify savings for the fiscal year that begins July 1.

The savings issue is a major concern of House Finance Committee Chairman Steven M. Costantino, D-Providence, who is leading the General Assembly’s efforts to balance a current-year deficit of $151 million and at least $384 for the coming year.

Governor Carcieri recently introduced a separate proposal to retroactively cap the number of credits redeemed every year, a move that would save nearly $25 million this year and $21 million in the next. Several real estate developers plan to sue the state if the governor’s plan becomes law, according to local developer Colin Kane, head of the Peregrine Group, which has invested $15 million in an East Providence development he says he would have to abandon.

Costantino yesterday suggested that the state’s fiscal woes might force the Assembly to adopt a retroactive plan.

“Let me tell you what this committee is facing in terms of retroactivity,” he said. “We made promises to locals, local aid this year. There’s a budget proposal to swipe $12 million. We made promises to kids on health care. There are proposals to throw those kids off.”

He continued: “I don’t like retroactivity. It’s not something that we like to do. But we made a lot of promises that we’re going to have to rescind.”

Edward F. Sanderson, executive director of the Historical Preservation and Heritage Commission, is among those who generally supported Fox’s bill, which many see as a compromise to the governor’s retroactive proposal.

He said the Wrentham House was an unusual example because it was designed by Richard Morris Hunt, “one of America’s major architects of the 19th century.”

“I don’t have a problem with high-end single-family residences being excluded from the program, mostly because there are so few of them,” Sanderson said.

There are only a handful of examples of social clubs and mansions benefiting from the tax credits, according to a list of active projects provided by Sanderson. But the vast majority of active developments are not major mill renovations.

Roughly two-thirds of all 150 active projects scheduled through 2012 are properties that contain fewer than 10 residential units. They stand to receive an estimated $125 million in tax credits of $276 million projected over the next four years.

Some of them are commercial developments; others are smaller historic properties clustered in the same neighborhood, which are renovated together and produce similar benefits as large mill projects, Sanderson said.

Proponents of the historic-renovation program acknowledge that lawmakers are faced with a challenging balancing act between the governor’s retroactive proposal and Fox’s bill.

“Balancing the … budget without a retroactive cap will be difficult, but balancing it through a retroactive cap will be catastrophic for our economic well being,” said Scott Wolf, executive director of the advocacy group Grow Smart.

speoples@projo.com