Apparently Lindsay Lohan was serious when she signed up to do her community service for that probation violation ... because TMZ has learned Lindsay already registered for community service.
Lindsay's lawyer went earlier this week to the Volunteer Center in West Los Angeles -- the place where defendants register for community service. Shawn Holley filed forms declaring Lindsay's intention to perform 360 hours of community service at the Downtown Women's Center.
Sources say Lindsay wants to start working at the Women's Center this week ... but the honchos at the organization want to wait 'til next week.
As for what Lindsay will be doing at the Woman's Center ... the decision has not been made. We're told the execs at the Women's Center will pick the job that "fits the skills of the person doing community service." As we first reported, one of the options is to work for D.I.V.A.S. -- a theatre workshop.