Lived by myself 6 months with custody every other weekend. recently rented a room from my ex and pay 1/2 the rent. Can I claim Head of Household?

You can qualify for Head of Household if you:

1. Were unmarried as of December 31, 2019 and
2. Paid more than half the cost to run your (or a qualifying parent's) home this year(rent, mortgage, utilities, etc.) and
3. Supported a qualifying person.

A qualifying child would be:

• Your child (including legally adopted), stepchild, foster child, sibling, half-sibling, step-sibling, or a descendant of any of them (for example, your grandchild or niece) AND
• Permanently and totally disabled OR under the age of 19 as of December 31, 2019 (under 24 if a full-time student) and younger than you (or your spouse, if filing jointly) AND
• Lived with you for more than half the year AND
• Single (or if the child is married, you'd have to qualify to claim them as a dependent even if you're not going to claim them as such).