Can I claim my partner's son as a dependent? My partner is unemployed and I financially support him and his son, year round. The boy's mom claims him as a dependent.

Can I possible claim Head of Household if he's not a dependant?

No, because in order to be HOH you have to support a dependent who is a blood relative.

Got it, thanks for all of your help.

If the child's other parent is claiming him, you cannot claim him also.  The child can only be claimed as a dependent on ONE tax return.

Even if you could claim him as a dependent, he would not be a qualifying child for the Earned Income Credit or Child Tax credit, or Head of Household because he is not related.