Donald Trump's former accountant slammed the Republican nominee's prowess regarding his taxes, saying "I did all the tax preparation."

"He never saw the product until it was presented to him for signature," Jack Mitnick, 80, who prepared Trump's taxes for nearly three decades, told Inside Edition in an interview broadcast Tuesday.

Mitnick last did Trump's taxes in 1996. He is now semiretired and living in Florida.

The New York Times reported Saturday a loss totaling nearly $1 billion that Trump reported on his 1995 taxes could have allowed the developer to avoid paying federal income taxes for as many as 18 years.

"I made my money as a successful private businessman following the laws of this country," Trump told a rally Tuesday in Prescott Valley, Ariz.

He said in Pueblo, Colo., on Monday: "As a businessman and real estate developer, I have legally used the tax laws to my benefit and to the benefit of my company, my investors and my employees.

"I have brilliantly used those laws," Trump told supporters. "I have often said on the campaign trail that I have a fiduciary responsibility to pay no more tax than is legally required, like anybody else, or put another way: to pay as little tax as legally possible."

Mitnick, however, told Inside Edition he used the tax code to benefit Trump.

"Right," he said. "I'm the one who did all the work."

He confirmed the authenticity of the documents provided to the Times.

"All the copies were delivered to Mr. Trump," Mitnick said. "Who got them after that, I can't tell you."