How long do I have to file a W2

No. You must file all of your 2016 income on your 2016 return. It cannot be included on your 2017 return. The only way to add another W-2 to your return after the original filing is by completing an amendment. You cannot e-file an amended return.  They have to be mailed, and it takes about 16 weeks for the IRS to process an amended return. 3 weeks after you mailed your amendment, you can start tracking its progress at the IRS Where's My Amended Return? site. Instructions can be found here:  https://ttlc.intuit.com/replies/5114064