“My job as finance director was to find ways to label extravagant personal spending as ministry expenses,” Ms. Koper said. This is one way, she said, the company avoids probing questions from the I.R.S. She said that the absence of outsiders on TBN’s governing board — currently consisting of Paul, Janice and Matthew Crouch — had led to a serious lack of accountability for spending.

Ms. Koper and the two other former TBN employees also said that dozens of staff members, including Ms. Koper, chauffeurs, sound engineers and others had been ordained as ministers by TBN. This allowed the network to avoid paying Social Security taxes on their salaries and made it easier to justify providing family members with rent-free houses, sometimes called “parsonages,” she said.

The company did not always succeed. Last year, officials in Orange County, Fla., turned down TBN’s application to register the adjacent lakefront houses in Windermere as parsonages, saying they served no religious purpose, The Orlando Sentinel reported. The designation would have resulted in religious exemptions and saved TBN roughly $50,000 in taxes a year.

Ms. Koper said that the company run by Matthew Crouch, 50, who is her uncle, had received an estimated $50 million in TBN money over the years, with little oversight, to finance religious film projects and television shows. TBN recouped only a small fraction of its loans and investments, sometimes forgiving large sums in return for broadcast rights of limited value, she said.

She also questioned the justification for providing rent-free houses for Matthew, now a TBN vice president, and his wife, Laurie, and separate houses for their young-adult sons in Costa Mesa, Calif., including one that Ms. Koper said was remodeled at company expense with wall-mounted Transformer robot figures costing several thousand dollars, a putting green and an indoor basketball court.

Ms. Koper and her husband, Michael Koper, 28, who formerly managed sales of TBN airtime, said they were fired last September after writing memorandums to the elder Mr. Crouch about questionable spending. They showed a reporter for The New York Times what they said were copies of the memos.