Mike "The Situation" Sorrentino and his brother Mark have yet to land trial dates for tax-evasion allegations, but their accountant has admitted enabling it.

Gregg Mark, 51, of Spotswood, pleaded guilty in a Newark federal courtroom Wednesday to one count of conspiracy to defraud the United States, according to the office of New Jersey U.S. Attorney Paul J. Fishman.

He risks up to five years in prison and a fine as high as $250,000. Sentencing is scheduled for March 24.

The case concerns millions of dollars that the Sorrentinos are believed to have accrued, through Mike's role in MTV's "Jersey Shore" series and related promotional events, as well as through MPS Enterprises LLC and Situation Nation Inc.

They pleaded not guilty to a seven-count indictment for conspiracy to defraud and filing false returns. Mike Sorrentino is additionally charged with failing to file a return.

Prosecutors allege that they hid income, and claimed personal expenses as business costs, including luxury cars, high-end clothes, and money transferred from business to personal accounts.

Mark admitted filing bogus business and personal federal tax returns for them related to tax years 2010 and 2011. Investigators estimate that the Internal Revenue Service (IRS) missed out on anywhere from $550,000 to $1,500,000.