Circumstances in which a person is to be treated as responsible or not responsible for another
77.—(1) Subject to the following provisions of this regulation, a person is to be treated for the purposes of the Act as responsible for a child or young person for whom he is receiving child benefit.
(2) In a case where a child (“the first child") is in receipt of child benefit in respect of another child (“the second child"), the person treated as responsible for the first child in accordance with the provisions of this regulation shall also be treated as responsible for the second child.
(3) In the case of a child or young person in respect of whom no person is receiving child benefit, the person who shall be treated as responsible for that child or young person shall be—
(a)except where sub-paragraph (b) applies, the person with whom the child or young person usually lives; or
(b)where only one claim for child benefit has been made in respect of the child or young person, the person who made that claim.
(4) Where regulation 78(7) (circumstances in which a person is to be treated as being or not being a member of the household) applies in respect of a child or young person, that child or young person shall be treated as the responsibility of the claimant for that part of the week for which he is under that regulation treated as being a member of the claimant’s household.
(5) Except where paragraph (4) applies, a child or young person shall be treated as the responsibility of only one person in any benefit week and any person other than the one treated as responsible for the child or young person under this regulation shall be treated as not so responsible.