Do you have a qualifying dependent in order to file as Head of Household? What do you mean by "Girlfriend accidentally selected the incorrect option. Would this disqualify me for a stimulus?"
Did your GF already prepare your tax return and e-file it? Or did your GF claim you as a dependent---please explain.
Am I Head of Household?
https://ttlc.intuit.com/questions/1894553-do-i-qualify-for-head-of-household
https://ttlc.intuit.com/questions/2900097-what-is-a-qualifying-person-for-head-of-household
If you qualify as Head of Household, when you enter your filing status (single or married filing separately) into MyInfo, and then enter your qualifying dependent, TurboTax will offer HOH as your filing status.
**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.**
