“Claimant” means a person who has filed a claim under this subchapter and who was domiciled in this state during the entire calendar year to which the claim for credit under this subchapter relates. When 2 individuals of a household are able to meet the qualifications for a claimant, they may determine between them as to who the claimant is. If they are unable to agree, the matter shall be referred to the secretary of revenue and the secretary’s decision is final.