[(1)]¹ In this Part—

“child” has the meaning given by section 8(3),

[“couple” has the meaning given by section 3(5A),]²

“the current year income” has the meaning given by section 7(4),

“employee” and “employer” have the meaning given by section 25(5),

...³

“the income threshold” has the meaning given by section 7(1)(a),

“joint claim” has the meaning given by section 3(8),

...⁴

“overpayment” has the meaning given by section 28(2) and (6),

“the previous year income” has the meaning given by section 7(5),

“qualifying remunerative work”, and being engaged in it, have the meaning given by regulations under section 10(2),

“qualifying young person” has the meaning given by section 8(4),

“the relevant income” has the meaning given by section 7(3),

“responsible”, in relation to a child or qualifying young person, has the meaning given by regulations under section 8(2) (for the purposes of child tax credit) or by regulations under section 10(4) (for the purposes of working tax credit),

“single claim” has the meaning given by section 3(8),

...⁵

“tax year” means a period beginning with 6th April in one year and ending with 5th April in the next, and

...⁶

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