In circumstances within the scope of Section 7-4-19 N.M. Stat. Ann. and in other circumstances where the revenues of this state would not be adversely affected, the secretary is authorized to enter into an agreement in writing with any person with respect to apportionment and allocation of that person’s income. Except upon a showing of fraud or misrepresentation of a material fact or a change in the statutory law, such agreement shall be conclusive. Any agreement, however, may be terminated by either party by written notice thereof to the other party at least ninety days before the beginning of the taxable year to which the termination applies.