(1)    In this Part “couple” means—

(a)    a man and woman who are married to each other and are members of the same household;

(b)    a man and woman who are not married to each other but are living together as husband and wife;

(c)    two people of the same sex who are civil partners of each other and are members of the same household;

(d)    two people of the same sex who are not civil partners of each other but are living together as civil partners.

(2)    For the purposes of this section, two people of the same sex are to be treated as living together as if they were civil partners if, and only if, they would be treated as living together as husband and wife were they of opposite sexes.

(3)    For the purposes of this section regulations may prescribe—

(a)    circumstances in which the fact that two persons are husband and wife or are civil partners is to be disregarded;

(b)    circumstances in which a man and a woman are to be treated as living together as husband and wife;

(c)    circumstances in which people are to be treated as being or not being members of the same household.