First of all, 2019 is not over yet. The IRS will not accept a 2019 tax return until late January at the earliest. Employers have until the end of January to issue your W-2's.
FILING WITH A PAY STUB
Please do not try to use your pay stub to prepare your tax return. It will not match the W-2 that you will get from your employer in just a few short weeks. You employer has until the end of January to give you your W-2. By waiting for your W-2 you will be able to file accurately. If you try to guess what goes in the W-2 “boxes” and mess up your return, you will need to amend. It takes about 4 months to amend a tax return.
The IRS will not be accepting 2019 returns until the end of January, so you CAN wait for your W-2.
FYI .... filing before your employer issues a W-2 is unwise for many reasons :
1) the info on the paystub will not match the W2 in most cases AND this will trigger an IRS audit AND/OR require you to amend the return which is a pain
2) the IRS will not process any return until they have the info from the employer to match to your return so filing early just puts you in a holding pattern with millions of others which can delay your return for weeks
3) any return with EIC or ACTC is automatically delayed in processing until after 2/15 no matter when you send in the return ... and in the past the early filers got stuck in the aforementioned holding pattern and their refunds were delayed
4) once again the tax forms have been redesigned so delays or bugs in the system will need to be worked out ... filing before these have been corrected can delay your return's processing as recent past history has proven ... in the case of the IRS the early bird doesn't usually get the worm, it only gets an unripened apple.
In addition you are required to have the W-2 in you possession prior to filing for 3 reasons:
1) You must physically attach a copy of the W-2 to a mailed tax return.
2) If you e-file you must retain the W-2 because the IRS can request that you send it to them at any time to verify the information so it must be in your possession.
3) You sign the tax return (either on paper or electronically) that the tax return is complete and accurate under penalty of perjury and without all the W-2 box information that can only be obtained from the actual W-2, it will not be complete or accurate.