For the purposes of subsection 721-30(3), a TSA contributing member left the group clear of the group liability if:
(a) the TSA contributing member ceased to be a member of the group at a time (the leaving time ) before the * head company's due time; and
(b) the cessation of membership was not part of an arrangement, a purpose of which was to prejudice the recovery by the Commissioner of some or all of the amount of the group liability or liabilities of that kind; and
(c) before the leaving time, the TSA contributing member had paid to the head company:
(i) if the contribution amount for that member in relation to the group liability could be determined before the leaving time--an amount equal and attributable to that amount; or
(ii) otherwise--an amount that is a reasonable estimate of, and attributable to, that amount.