I am away from home how can I file my fourth quarter estimated tax return and pay for it?

you can go to the IRS website, download the 4th quarter 1040-ES for 2021 and mail it in. or if you're registered with the IRS you can pay online

https://www.irs.gov/pub/irs-pdf/f1040es.pdf 

https://www.irs.gov/payments 

Web Payment directly with the IRS

There isn't really anything to "file" if you use the IRS Direct Pay website....but you do need to indicate it is a 2021 estimated payment when you pay.

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Direct Debit from your bank account if you know your routing and checking account numbers:

https://www.irs.gov/payments/direct-pay

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or...Pay with a Credit or Debit Card:

https://www.irs.gov/payments/pay-your-taxes-by-debit-or-credit-card

What ? Everything is done on the Internet nowadays.