I already filed my tax return but forgot to add a second w2. How do I add it?

Unfortunately, you cannot add a second W-2 to your return that has already been filed.   

You must wait for the IRS to accept or reject the return.

If the return has been rejected by the IRS, you can add the second W-2 to your return before you refile the return.

If the return has been accepted by the IRS, you must file an amended return to include the second W-2.