How long have you been in the US on your F-1 visa?

This is my 6th year, and I think I should file 2017 tax as a residential alien. My question are 1) is earned income credit applicable for F1 visa holder? Including state credits of rent? Because I found the software asked questions about the rent; 2) can I efile my tax return?

If you are on an F-1 visa and you meet the substantial presence test for the entire 2017 calendar tax year then you will be considered a US resident for US income tax purposes for 2017. You would be entitled to the earned income credit if you qualify (one of the requirements being that you have a valid Social Security Number) and you would be able to efile your return.

Please note - - If you are on a F-1 visa, you will be exempt from the Substantial Presence Test for the first 2 (if non-student) or 5 (if student) calendar years that you are in the US.

TurboTax does not support Form 1040NR. You may want to try https://www.sprintax.com/ which is specifically designed to help international student nonresident aliens with their US tax returns.

Here is a link to the IRS website for Form 1040NR, U.S. Nonresident Alien Income Tax Return