(CNN) -- Former Detroit Mayor Kwame Kilpatrick violated his probation by failing to report assets that could be used to pay restitution, a Wayne County, Michigan, judge ruled Tuesday. The judge delayed sentencing for 30 days.
Judge David Groner told Kilpatrick, "You would be well-advised to have your affairs in order."
Kilpatrick pleaded guilty in September 2008 to two felony counts of obstruction of justice stemming from his efforts to cover up an extramarital affair. He also pleaded no contest to charges of assaulting a police officer attempting to serve a subpoena on a Kilpatrick friend in that case.
He was accused of blocking a criminal investigation into his office and firing a police deputy to cover up the affair.
He served 100 days in jail and was released to five years of probation in February 2009. He was ordered to pay $1 million in restitution as part of his original plea deal.
After ruling that Kilpatrick had violated probation by failing to turn over his tax return, Groner set sentencing for May 20.
Both the prosecution and defense will get two days before that date to review a Michigan Department of Corrections presentence report, also provided to the court.
The judge noted Kilpatrick had just made a payment of $3,000 on his restitution bill.
"That's' $3,000 more for the city of Detroit, and I bet he makes another $3,000 payment next month," Groner said. "Let's get the money if we can. If I put him in jail, it's your tax dollars, Wayne County, and if he's in jail, the county doesn't get that money."