Here's places where to mail different forms
Where to mail federal paper returnshttps://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment
Where to mail a 1040V voucher paymenthttps://www.irs.gov/pub/irs-pdf/f1040v.pdf
Where to mail form 4868 Extension on page 4https://www.irs.gov/pub/irs-pdf/f4868.pdf
