Do you mean a return for someone else? You cannot file a second tax return for yourself. If you filed a tax return and left out some of your income etc. you have to wait for the first return to be fully processed and then prepare an amended return.
If you mean you need to prepare a return for some other person:
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
