Crediting of Class 3 contributions
3. Where, for any year, a contributor’s earnings factor derived from—
(a)earnings upon which primary Class 1 contributions have been paid or treated as paid;
(b)credited earnings;
(c)Class 2 or Class 3 contributions paid by or credited to him, or
(d)any or all of such earnings and contributions,
falls short of a figure which is 52 times that year’s lower earnings limit for Class 1 contributions by an amount which is equal to, or less than, half that year’s lower earnings limit, that contributor shall be credited with a Class 3 contribution for that year.