Thank you for your question.
You can prepare your taxes for filing without a W-2, however.
1. The IRS requires a copy of your W-2 when you file your return by mail.
2. When you file your return electronically, you are required to input information from your W-2. While it is possible to input information without your W-2, you have no idea what the final figures are in the various blocks that are part of the W-2.
Your pay stub in most instances does not totally match the W-2 block for block.
That is you pay stub does not say...block 1, block 2 etc of form W-2. Your employer may allocate part of that pay stub information to a category block on the w-2 that is not reflected by your entries.
So when you finally get a W-2, you may have to file an ameded tax return using form 1040X,
AND if you electronically file without a W-2, and the information reported to the IRS on the IRS W-2 and transmittal W-3 does not match what you put, then it will cause a rejected return or delays in processing.
In addition with some electronic returns, you may recieve back a request to submit documents, meaning you may have to mail documents to the IRS.