Government Contractor Positions

What the hell do I get to work? I'm confused!?
I got a job with a government contractor, my position will work office in a database. I really have no idea what it should be formal. My job is responsible for IT. I worked as a technician on site for many years and have always been the kind that crop through attics and other dirty things, so I was always in uniform. I know how to handle this job, I just have no idea how dress? Any ideas? I'll be doing easy things, a lot of paperwork, but nothing dirty.
You should dress in a suit for the first week (for at least the first day), but I am sure that the IT department will be a kind of necklace with khaki long-sleeved shirt instead.
Federal Government GSA Schedule Information