WASHINGTON (CNN) - A congressional report to be released Thursday will detail the "complete story" of Enron's elaborate practices to avoid paying taxes and an "eye-popping account" of the failed company's compensation for executives, according to the committee's chairman.

The Senate Finance Committee will release the report during a hearing, a year after it asked a congressional panel to investigate Enron's tax records and practices.

Witnesses will testify at the hearing, which starts at 10 a.m. ET, to further back up the reports claims.

Sen. Charles Grassley, R-Iowa, the committee's chairman, on Wednesday described the report as "an absolute barn-burner."

"The report is very disturbing," he said.

Grassley said it gives the "complete story of Enron's efforts to manipulate its taxes and accounting" and provides an "eye-popping account of executive compensation."

One committee source will show that Enron "engaged in elaborate transactions and machinations to get out of paying taxes, seemingly whenever possible."

"Companies like Enron have a strong advantage over the IRS, which is limited by assertions of attorney-client privilege in getting access to documents that would allow the IRS to go after bogus tax avoidance," this source said. "This report will be very critical and instructive as Congress determines how to put corporations, the IRS, and most of all, average taxpayers who pay their taxes, on a level playing field."

Grassley and ranking member, Sen. Max Baucus, D-Mont., asked for the investigation last year, saying it is critical toward shaping legislation that curbs questionable tax activities.

Last month, a Senate subcommittee looking into Enron's practices recommended that the Security Exchange Commission and federal bank regulators take joint action to fill what it said is a gap in federal oversight that allows financial institutions to get away with accounting misconduct.

Enron, once a heralded energy powerhouse, became synonymous with corporate disaster when it filed for bankruptcy in December 2001 after its stock plummeted in the previous months. Several investigations into the company's behavior continue, and its chief financial officer, Andrew Fastow, faces trial on 78 counts of wire fraud, money laundering and conspiracy.

--CNN Money producer Scott Spoerry contributed to this report.