The following definitions apply to rules found in this subchapter:

(1) "Injured spouse" means a taxpayer who does not owe a child support obligation, but who has reported income on a joint return with a taxpayer who does owe a past due child support obligation.

(2) "Innocent spouse relief applicant" means a taxpayer who has filed joint federal and Montana tax returns for the same tax year, has obtained relief from a joint and several federal tax liability under section 6015 of the IRC, and is requesting relief from a joint and several Montana income tax liability.

(3) "Obligated spouse" means a taxpayer who is liable for a past due child support obligation.