Do you have to file all of your W-2s even if some of them are under 600 or do you only file the W-2s over 600?

Think of it this way, the IRS has all your W-2s. If you don't report them all, they will know that you are ducking out on paying taxes. There isn't anything magic about the number $600. I suspect you intended to ask about 1099 under $600, not W-2. (Especially as anything on a W-2 probably has withholding and other benefit payments like FICA and Workmens Comp, etc., that you would want to assure are refunded or credited as the case may be). Yes, many times different types of income required to be reported on a 1099 are excluded from the reporting requirement if the amount to report is under $600. A 1099 for non employee compensation, as well as payment to non corporate entities are some that come to mind. Other thresholds exist for other types of items. However, those exemptions are from the 1099 issuers side, basically to avoid having to track and produce a zillion rather minor transaction types. It does not exempt the receiver from having to report the income, no matter what the source or how small. Hence, the answer, or result essentially remains the same.