I have been working in California on H1B visa since Sep 2015. In Nov 2018 I moved to Germany permanently. How can I file my tax returns for the year 2018?

[pk]

You will need to file a form 1040 as a resident of the USA and be taxed on world income -- this is for the period you were present in the USA. If you had  income from the USA sources thereafter that also needs to be included in your filing.  The issue here is that  it is unclear from your post, if you went through a process to cancel your visa before leaving USA -- if you have then the  above is true because thereafter you became a Non-Resident Alien.  If you did not , then USA will claim your world income through the end of the year and give you tax credit for any taxes paid to Germany ( i.e. the portion taxed by both countries ).

You can use TurboTax to file your return -- will need a US issued card  ( with US billing address ) to pay for the services.  IRS can  direct deposit / debit from your US bank account ( it is very strongly recommended  and now hoped  that you have a USA bank account active for at six months past your leaving the country ).

Is there  more I can do for you?

Namaste ji