How do I file taxes for my parents

prepare a joint return. it can not be the same account as yours since the last one prepared destroys the pervious one. however, you can use the same e-mail address.

1. Power of Attorney (POA): If you have a power of attorney (POA) for your parents, you can sign their tax return on their behalf. Attach a copy of the original POA to Form 8453 and send it to the IRS once the return is accepted. Make sure to follow the guidelines in Publication 17, Your Federal Income Tax For Individuals.

 Power of attorney. A return signed by an
itgent in any of these cases must have a power
of attorney (POA) attached that authorizes the
agent to sign for you. You can use a POA that
states that the agent is granted authority to sign
the return, or you can use Form 2848. Part I of
Form 2848 must state that the agent is granted
authority to sign the return.
Court-appointed conservator, guardian, or
other fiduciary. If you are a court-appointed
conservator, guardian, or other fiduciary for a
mentally or physically incompetent individual
who has to file a tax return, sign your name for
the individual. File Form 56.

https://www.irs.gov/pub/irs-pdf/f2848.pdf 

TurboTax does not have form 2848

so you'll need to get it from the IRS website.be sure to read instructions

it does do form 8453 but i don't see how you can check the 2848 box