Can my nephew use my turbotax to file his tax

[AngelG]

If you want to prepare another return using TurboTax Online, you will need to set up another account.  TurboTax Online is set up to be one tax return per account, however you can have up to 5 accounts per email address.

See the TurboTax FAQ below for instructions on how to set up another account to prepare another return.

https://ttlc.intuit.com/replies/3288574

[NiaW]

He will need to create his own account because the online editions are only good for completing one tax return per account and user ID. See the FAQ below to find out how you can create a new account:

https://ttlc.intuit.com/replies/3288574