The federal sentencing guidelines are advisory, and judges may impose sentences that are either heavier or lighter than the advised range. The plea agreement also notes that Ms. Huffman “reserves the right to argue” that her crime actually corresponds to a lower guideline — of zero to six months of incarceration.

[Read more on the question of prison time in the college admissions case.]

According to the charges, Ms. Huffman paid $15,000 to William Singer, a consultant at the center of the case, so that a proctor would correct some of her daughter’s answers on the SAT after the girl had finished the test and left. Mr. Singer has pleaded guilty to racketeering and other charges. Ms. Huffman’s daughter, who was apparently unaware of her mother’s plan and to whom Ms. Huffman has publicly apologized, is still in high school.

Twelve other parents charged in the case have said that they will plead guilty. Prosecutors are arguing for longer sentences than the one proposed for Ms. Huffman in the cases of several of the other parents, because they are accused of paying more money as part of the scheme.

In the case of Bruce Isackson, who has agreed to plead guilty to conspiracy to commit fraud and money laundering and to defraud the United States, prosecutors have said they will recommend a sentence at the low end of a guidelines range of 37 to 46 months. Prosecutors accused Mr. Isackson and his wife, Davina, of paying Mr. Singer a total of $600,000 to facilitate cheating on the ACT for one daughter and to get two daughters admitted to the University of California at Los Angeles and the University of Southern California as athletic recruits.

More than a dozen other parents, including the actress Lori Loughlin and her husband, the designer Mossimo Giannulli, have pleaded not guilty.