A Republican congressman claimed Thursday that the scandal-besieged General Services Administration might be caught up in more questionable behavior -- possibly seeking "kickbacks" from contractors who work on energy-efficient buildings. 

Rep. Charles Boustany's questions revolve around an obscure tax deduction for companies that work on energy-efficient buildings. He said documentation shows the GSA might have been trying to demand a 19 percent kickback -- from the deduction itself -- for companies that do this work. 

Though the GSA is now denying that the program ever got off the ground, Boustany expressed concern about where that money could have been going -- considering the hundreds of thousands of dollars GSA has spent over the last several years on lavish trips and conferences. 

"The action by the GSA raises a number of serious questions about whether this particular tax deduction is being abused. Requiring a cash payment in exchange for a tax deduction is a kickback, pure and simple," Boustany said in a written statement. "We must ensure that this tax deduction is being used for its intended purpose and not being sold to line some government slush fund.

"Given the wide range of abuse of taxpayer dollars being used for everything from fortune tellers to clowns to spaying pets, it is clear that strong and vigorous oversight is necessary to ensure that taxpayer dollars are being protected." 

Boustany, R-La., in making the claim, released an undated document that appeared to be a boilerplate letter from the GSA to prospective contractors. It discussed the tax deduction -- but then said GSA would allocate that deduction "upon payment to GSA of 19 percent of the deduction amount." 

The letter claimed the money would be used "by GSA to invest in additional energy-efficiency projects." 

GSA released a statement Thursday afternoon acknowledging the "pilot" program existed but claiming no money was ever paid back to the agency. 

"In May 2011, the General Services Administration launched a small pilot program to reinvest funds for energy efficiency upgrades on federal buildings," the GSA said. "In December 2011 the pilot program ended. During that seven month period, no contractors took part in the program and no money was paid to the GSA." 

Boustany sent letters Thursday not just to GSA, but more than a dozen other departments and agencies in an apparent attempt to see if the practice was widespread. 

He's asking the department to provide copies of the letters they send to contractors regarding the deduction, as well as disclose whether they requested a "percentage of the deduction amount" back and how that money might have been used.