@NCperson Thanks .
I filed tax for my child with ITIN number for year 2019. and in early of 2021, I paid additional tax from IRS web site so that to extend my tax return automatically. You can get an automatic extension when you make a payment with Direct Pay
I filed my tax return on 12 Oct 2021 by paper mail. as I just got my kids' SSN number on the end of Sep 2021. so I filed my tax with turbotax software on the early of Oct 2021 with my kid's SSN number.
I didn't attached my children SSN paper copy as I think IRS should get it from their database.
I doesn't have transcript on extension. but I should be able to find the electronic transfer record when I pay additonal tax to IRS in the early of 2021.
