After you file

AND...the IRS has already told Congress (House) they can implement without Taxpayers being required to Amend.

...Your tax return, as-filed already, has the required information for their computers to calculate what extra they may be able to send you.

 

BUT #2:  It would still take 6-12 weeks to implement.....lots of computer code to write and debug.

____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*