Feldman's parents managed his career until money came between them and the young star.
"I got legally emancipated by going to the [Screen Actors Guild] producers pension, health and welfare plan myself at 14 years old and saying, 'What were my earnings, and what's left?'" Feldman said.
He said he was told he had earned about $1 million, "which is really not that much money, but in those days it was," and $40,000 was left.
"And guess what? When I went in for the emancipation trial, my father said, 'Since I spent my time with you on your last film and took it away from my office where I should have been focused, instead I'm going to ask you for that $40,000 back as repayment for the money that I lost in my business,'" Feldman said.
He had to pay his father, he said, putting him in debt at the age of 15.
Court records of the trial are sealed. In a statement to ABC News Feldman's father said, "I love my son with all my heart however his lifestyle has impaired his memory. I opposed his emancipation because he was not mature enough to face life in the world of show business. I feel the court made a mistake in allowing him to be on his own and out of control. Any money that the court awarded is a fraction of his claim and this was reimbursement for strictly professional expenses since after Corey's Mom and I separated she received Corey's income and I ended up with his expenses, ie: private school, a publicist, professional wardrobe, traveling expenses and lots more. This helped to save his career while he was in trouble with drug problems. I thought I was doing the best for my son and I am always here for him."
Being underage and famous is not a dream Feldman has for his son, he said, and unlike many famous parents, he doesn't walk the red carpet with him.
"Child stars have nothing," he said. "They have no choice. ... I was never taught how to have a family. I was never taught how to raise a child, because I wasn't raised properly. I was never taught how to care for somebody, because I was never shown genuine love."
"I knew how to read a contract by 10 years old, but I didn't know what it meant for somebody to come in and tell me they loved me and kiss me goodnight," Feldman added. "That's a problem."
Watch the full story on the "Primetime Nightline: Celebrity Secrets" special "Underage and Famous," airing TONIGHT at 10/9c on ABC