Upon the completion of the investigation, the commissioner of the department of health and human services shall decide whether the applicant is eligible for assistance under the provisions of this chapter or N.H. Rev. Stat. Chapter 161 and shall determine in accordance with the rules of the department the amount of such assistance and the date upon which assistance shall begin. The commissioner shall, however, in all cases, first consult with the proper officials of counties hereby required to contribute to the cost of the assistance. The commissioner shall notify the applicant of his decision and send a copy of the decision to the proper county officials.