You cannot efile amended returns. They must be paper filed only.
If you have not yet filed your 2019 return, the IRS will defer to your 2018 filing. If you file jointly, the phaseout will be based on your joint income. It is not likely that the IRS would process your amended 2018 return prior to processing the stimulus payments.
Any amounts due will be reconciled when you file your 2020 taxes. Therefore, if you filing jointly in 2020 and would have qualified for the joint stimulus payment, it will appear as an additional credit on your return. However, this will not occur until filing in 2021.
The following resources may be helpful:
What do I need to know about the coronavirus stimulus package?
IRS Coronavirus Tax Relief
TurboTax Corona Virus Tax Center Updates
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
