Section 1 Outline of contributory system.

for paying such benefits under this Act F1or any other Act as are payable out of the National Insurance Fund and not out of other public money; and

for the making of payments under section 162 of the Administration Act towards the cost of the National Health Service,

Class 1, earnings-related, payable under section 6 below, being—

Class 1A, payable under section 10 below F5... by persons liable to pay secondary Class 1 contributions and certain other persons;

Class 1B, payable under section 10A below by persons who are accountable to the Inland Revenue in respect of income tax on F7general earnings in accordance with a PAYE settlement agreement;

Class 2, flat-rate, payable F8... under section 11 below by self-employed earners;

Class 3, payable under section 13 F9or 13A below by earners and others voluntarily with a view to providing entitlement to benefit, or making up entitlement;

Class 3A, payable by eligible people voluntarily under section 14A with a view to obtaining units of additional pension; and

Class 4, payable under section 15 below in respect of the profits or gains of a trade, profession or vocation, or under section 18 below in respect of equivalent earnings.

be subject to regulations under sections 19(4) and 116 to 120 below; and

to the extent provided for by Part IX of the Administration Act be subject to alteration by orders made by the F11Treasury from year to year under that Part,

shall have effect with respect to the computation, collection and recovery of contributions of Classes 1, 1A, F131B, F14, 3 and 3A, and otherwise with respect to contributions of those classes; and

shall also, to the extent provided by regulations made under section 18 below, have effect with respect to the computation, collection and recovery of Class 4 contributions, and otherwise with respect to such contributions, F15....

be liable to pay Class 1, Class 1A F20, Class 1B or Class 2 contributions unless he fulfils prescribed conditions as to residence or presence in Great Britain;

be treated under section 11(5B) as having actually paid Class 2 contributions unless he fulfils such conditions;

be entitled to pay Class 3 contributions unless he fulfils such conditions; or

be entitled to pay Class 1, Class 1A , Class 1B or Class 2 contributions other than those which he is liable to pay, except so far as he is permitted by regulations to pay them.