suggest re-reviewing the terminology. It's cumbersome to say the least.
HOH requires a "Qualified PERSON" (QP), which may be neither a Qualified Child or a Qualified Relative (QR). It's a third definition.
While the definition of a QP and a QR are similar, they are not the same.
For a QP, the person has to be a biological relative (cousins excluded and some in-laws included); for a QR, it can be any biological relative or any non-biological individual
For a QP, the person must live with the taxpayer for at least 6 months of the year (parents excluded); for a QR, there is no residency requirement for the biological relative but there a full year residency requirement for the non-relative.
For example, a domestic partner can be a Qualified Relative if the partner lives with the Taxpayer for ALL 12 months of the year, earns less than $5200 (2025), the taxpayer provides more than 50% of support, etc . But because there is no biological relationship, this indiviudal can not be a Qualified Person.
See Table 4 on Page 10.
https://www.irs.gov/pub/irs-pdf/p501.pdf
