NBC News reports that Huffman, 56, was accused of paying $15,000 to have wrong answers corrected on daughter Sofia Grace Macy's SAT exam.
The Oscar-nominated actress, who is married to actor William H. Macy, agreed to plead guilty last month to charges of conspiracy to commit mail fraud and honest services mail fraud.
Prosecutors have recommended the actress receive four months behind bars. Huffman is scheduled to be sentenced Sept. 13.
The actress broke down in tears while explaining that she had requested, for legitimate medical reasons, extra time for Sofia Grace to take her test. The teen has been seeing a neuropsychologist since she was 8, Huffman says.
"I just didn’t want to create the impression that the neuropsychologist had any involvement because she, like my daughter, didn’t have any knowledge of my actions, of what I had done," Huffman said.
Joining Huffman in pleading guilty in a federal courtroom in Boston was Los Angeles businessman Devin Sloane, who paid $250,000 for his son to be admitted as a phony water polo recruit at the University of Southern California.
Five parents have now formally pleaded guilty in connection with the college admissions scandal. Nine others have made agreements with prosecutors to plead guilty at a later date.
The actress has said her daughter had no idea what was being done on her behalf. Sofia Grace was a student at Los Angeles High School for the Arts, when her mom was arrested in March.
Huffman paid the money to a fund controlled by William Rick Singer, who ran a business getting the children of his clients into prestigious universities.
He took thousands of dollars from clients to either boost standardized test scores of their teenage children or pass them off as elite athletes.
Singer pleaded guilty in March to racketeering and other charges.
Schools such as Yale University, Stanford University, USC, Wake Forest University and Georgetown University, among others, were implicated in the probe dubbed "Operating Varsity Blues" by federal agents.
Video from CBS Los Angeles: