Generally agreeing with @macuser_22 --- (a) the parents are divorced but are they living in state that recognizes common-law marriage and are they holding themselves out as a couple ( even if they are divorced); (b) if they are really divorced for intents and purposes and are not married to anyone else, then the parent that is maintaining a household for the underage qualifying child/children can indeed claim that child for HoH purposes ( because "considered unmarried " rules will not apply; the other parent is single and therefore can claim another qualifying child for her deduction/child credit purposes. (c) However, both the divorcees living under one roof , co-mingling their earnings and expenses ( assumed ), while not unheard of , could be challenged as to the intent of action.
