I started a 401k this past tax year. Can i still use the free filing or do i have to pay for the return now?

[xmasbaby0]

You do not enter that you "started" a 401k.    If you took any money out of the 401k you will have to enter a 1099R for that.   if you have just had a 401k through your employer, you will be entering the necessary information about that when you enter the boxes from your W-2.

The software might try to give you a retirement saver credit.  If the credit is so small that would rather not upgrade to Deluxe to use the saver credit, tell the software in My Info that you are a student, and it will take the credit away and prevent the upgrade.

Or....get the credit using other free software

Use this IRS site for other ways to file for free.  There are 8  free software versions available from the IRS Free File site

https://apps.irs.gov/app/freeFile/