Mr. Cooper, who had been scheduled for release in August, was 66.

Mr. Cooper’s business involved soliciting investors who would pay up to $1,200 plus $100 a month for each “package” of tax-avoidance methods they received, with promises that their income tax obligations would shrivel.

The Tax People was the subject of a front-page article in The New York Times in September 2000, part of a series on tax schemes that was awarded a Pulitzer Prize.

That article examined Mr. Cooper’s claims that “golf, hunting, fishing and even vacations with your family” could become tax-deductible expenses for those who bought the company’s system. The Tax People boasted that its “Tax Dream Team” included former I.R.S. officials who were such powerful advocates for the Cooper system that I.R.S. auditors had wilted before them. One team member was Jesse A. Cota, a former I.R.S. district director in California.

In an interview in his San Diego hotel suite in 2000, Mr. Cooper told a reporter that dropping a business card in a fishbowl at a restaurant’s cash register made the meal, parking and mileage to and from the establishment tax-deductible. Asked by The Times to identify a statute, regulation or court case authorizing such deductions, Mr. Cooper said the answer was in his company’s promotional materials. Advised that no authority was cited in those materials, Mr. Cooper said the right to such deductions was common knowledge. He then said that one of his “Tax Dream Team” experts would explain. When asked which team member should be queried, Mr. Cooper stood up and walked out of the room.

Carla Stovall, the Kansas attorney general at the time, asked a state court in 2001 to shut down the business. At a civil court hearing, Charles W. King, a professor of marketing at the University of Illinois at Chicago, testified that The Tax People was a legitimate marketing firm.