Amend 2018 filling Status and w7 for non resident spouse

[AK277]

Hi,

I am married to foreign spouse since August 2018,  i filled my 2018 return as single . now i came to know that i should file as married filling jointly by claiming my foreign spouse as resident alien for tax purpose, for that purpose i need  Individual Taxpayer Identification Number (ITIN) for my spouse. as per IRS i can send W7 with form 1040. 

Ideally i should be sending w7 with 2020 tax return, but i am out of time to amend 2018 to get maximum credit. 

my question : Can i send w7 for my wife with 2018 Amend 1040X. 

https://www.irs.gov/individuals/international-taxpayers/nonresi[product key removed]e#:~:text=If%20y... 

[JeffreyR77]

You are not out of time to amend your 2018 tax return.  Your have 3 years from the original due date of the 2018 tax return or until April 15, 2022 to file an amended tax return for tax year 2018. 

You should file your 2020 tax return with a Form W7.  When you receive your ITIN, you can amend your 2019 and 2018 tax returns to claim any additional credits you may be entitled to.

 File Your Return & Request An ITIN 

[Critter-3]

Just to be clear ... you attach the 1040 to the W-7 and mail them both to the W-7 processing address.  Once they issue an ITIN the tax return is forwarded along with the ITIN for processing.   DO NOT  do it the other way around.   Once the ITIN is issued they will mail it to you and then you can amend the prior year returns as needed.