Los Angeles (CNN) -- Lindsay Lohan must start serving a 30-day jail term next week after admitting that she violated her probation on a necklace theft conviction, a Los Angeles County judge ordered Wednesday.
"It's possible she could be booked in and booked out" the same day, Los Angeles County Sheriff spokesman Steve Whitmore said Wednesday afternoon.
"It depends on the fluctuations of the day, what's going on in the jail," Whitmore said.
After that, the actress must work at least 12 days a month at the county morgue until she completes the 53 remaining days on her court-ordered community service and she must attend 18 psychotherapy sessions, Judge Stephanie Sautner told her.
If Lohan misses any of those goals, she will be returned to jail for another 270 days, the judge ruled.
"This is what we really call putting the keys to the jail in the defendant's hands," Sautner told Lohan.
The actress, who admitted violating her probation during a hearing Wednesday, must report to the Los Angeles County jail by November 9, the judge said.
"You are not to get house arrest or early release, except for that required by the law," Sautner said.
Whitmore said that the early release program is part of the law, meaning Lohan would likely get out quickly due to overcrowding.
When Sautner sentenced Lohan to 120 days in jail last May, she ended up serving 35 days of home confinement instead, due to jail overcrowding and state rules that give prisoners credit for good behavior.
It was not immediately clear how many days Lohan will actually serve this month, if she ends up getting credit for good behavior.
Prosecutors said Lohan missed 12 of 20 scheduled workdays at a downtown Los Angeles women's center, part of the court-ordered community service imposed in May when she pleaded guilty to stealing a necklace from a Venice, California, jewelry store.
Lohan, 25, was already on probation for two drunken driving convictions from 2007.
She also canceled 14 of 19 scheduled appointments for court-ordered psychotherapy, they said.
"From what I see of you, you need a structure," Sautner told Lohan Wednesday, instructing her to return to court each month, starting December 14, to show she is complying with the schedule.
If the actress stays on track, her probation would be eased on March 29, 2012, Sautner said. If she doesn't keep up with the requirements, she will serve the additional 270 days behind bars, the judge said.
The full sentence imposed Wednesday was 150 days for the necklace theft probation violation and 150 days for violating probation on the 2007 drunk driving conviction in Beverly Hills.
While the original sentence included 360 hours of community service at a downtown Los Angeles women's center, the judge said she did not want to put the Skid Row charity through the pain of Lohan again.
When the judge called The Good Shepherd Center for Homeless Women, the charity refused to take Lohan on as a worker "saying you were a bad example," Sautner said.
But Lohan seemed to find a good fit with her work at the Los Angeles County morgue, where Deputy Chief Coroner Ed Winter said she worked four days in the past two weeks cleaning up.
"So, the morgue is willing to keep you," the judge said.
All of her community service work has been transferred there, she said.
Two weeks ago, the actress' father, Michael Lohan, told HLN's "Issues with Jane Velez-Mitchell" program that his daughter shouldn't be in jail, but in rehab.
Last week, Michael Lohan was arrested twice in two days for violating a court order to stay away from his former girlfriend. CNN learned Wednesday that he is now in an "administrative confinement" cell in the infirmary section of Orient Road jail in Tampa, Florida, where he's awaiting trial.
Lindsay Lohan's legal woes, which began four years ago with two drunk driving arrests, have been compounded by her failure to attend counseling classes, and alcohol and drug test failures.
Her probation is scheduled to end within a year unless Lohan breaks any laws before then. It has been extended several times because of violations, including the failed alcohol and drug tests."It's possible she could be booked in and booked out" the same day."
CNN's Michael Martinez contributed to this report.