Your W-4 does not dictate how you file your tax return. If he has no qualified dependents to file as HOH he will file as Single. He cannot claim you as a qualified dependent---you are not related to him. If he did not have enough tax withheld from his checks---which might be the case---he may owe when he prepares his return.
He might want to change his W-4 going forward. He cannot file a tax return as HOH without having a qualified dependent.
https://www.irs.gov/individuals/tax-withholding-estimator
https://www.irs.gov/pub/irs-pdf/fw4.pdf
**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.**
