TMZ has learned Charlie Sheen may not be serving 30 days in jail ... only 30 nights.
An official in the Pitkin County jail tells us Charlie is eligible for work release -- meaning he could do volunteer work in Aspen where he would spend his days, and come back to the jail to sleep at night.
We're told when Charlie goes to court on Monday to plea bargain his case, the judge can declare him eligible for work release. Then it's up to the Sheriff to decide if Charlie meets the criteria for work release ... which includes working at a productive job in the community. If the criteria is met, Charlie would get a daytime pass.
As we first reported, even though Charlie will plead no contest to 3rd degree misdemeanor assault and accept a 30-day sentence, he will only serve 17 days if he's a good boy and two of those days (the first and last) could be nothing more than a few minutes behind bars.