I have my last check stub but not my W-2 how can I look up my employer federal tax ID number

[Anonymous]

you can't.  there is no data base containing ein's except by the IRS and it is not accessible,     in addition you are asking for trouble trying to enter your W-2 from paystubs.    the actual w-2, which doesn't have to be issued until january 31, 2020, might contain additional info.    then you will   have to wait until the IRS processes the first return to file an amended  return. It is also possible that the IRS will send correspondence if it's copy and what you file don't match.   Efiling has not opened and thus your rturn will sit on IRS computers and if you receive a w-2 that doesn't match, you can not recall the return to fix it.  

[Carl]

EIN's are just like SSN's and are not publicly available. You have to have a "legal" need for it. So it will be on your W-2 when you receive it, because you will have a legal need for it, in order to file your taxes. It won't be on your pay stub, becuase you don't have a legal need for it, in order to get paid.