except that with respect to the disposable earnings of any individual for any work week, the fifty per cent (50%) specified in paragraph 1. shall be deemed to be fifty-five per cent (55%) and the sixty per cent (60%) specified in paragraph 2. shall be deemed to be sixty-five per cent (65%), if and to the extent that such earnings are subject to garnishment to enforce a support order with respect to a period which is prior to the twelve (12) week period which ends with the beginning of such work week.
Idaho Code § 11-207