The acheivement is nearly unmissable, due to where it is, and the earliest place you can get it is level 2.
Without spoiling too much, well into level 2 you will come to a point where you need a wrench to open doors to progress. When you crawl through a vent system the ID Tag is on the floor next to the wrench. It looks like a credit card sized ID card with some string round it to go round you neck and emits a glow on the floor.
Pick it up and the acheivement is yours!