No, a taxpayer cannot use the head-of-household filing status if the taxpayer’s only dependent is his or her registered domestic partner.
To qualify for the head-of-household filing status, a taxpayer must provide more than half the cost of maintaining a household that is the principal place of abode for more than half of the taxable year of a qualifying person. According to section 2(b) of the Internal Revenue Code, a qualifying person must be a specified related individual as defined in section 152(c) or (d). A registered domestic partner does not meet the criteria of a specified related individual under these sections, even if the registered domestic partner is the taxpayer’s dependent. Therefore, a taxpayer whose only dependent is a registered domestic partner does not qualify to file as head of household.
Sources:
Publication 501 (2023)
§ 2. Definitions and special rules
IRS FAQ
