What do you need to mail? TAS is the Taxpayer Advocate Service
https://www.taxpayeradvocate.irs.gov/
Where to mail federal paper returns
https://www.irs.gov/uac/where-to-file-paper-tax-returns-with-or-without-a-payment
Where to mail an amended 1040X return, see page 20
https://www.irs.gov/pub/irs-pdf/i1040x.pdf
