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You only need W-2's if the company physically doesn't exist anymore. Can't get them right away, don't worry, you have a bit, but your background check can't be finished until you have it all. Take some initiative and call ALL your old employers, even the YMCA, as for someone who can verify employment, get their name and number, and that's all you'll need, oh, and the address also. If you can't GET EVERYTHING by orientation time, you won't be flogged for it.