(1)  If it is difficult or impracticable for the Commissioner to determine a person's tax liability under a taxation law without undue delay or expense because of the complexity or uncertainty of the case or for any other reason, the Commissioner may make an assessment of that liability in accordance with this section.

(2)  The Commissioner, with the agreement of a person, may assess the person's tax liability in an amount specified in, or determined in accordance with, the agreement.

(3)  The Commissioner must not make a reassessment of a tax liability assessed under this section –

(a) except with the agreement of the taxpayer; or

(b) unless, in the opinion of the Commissioner –

(i) the assessment under this section was procured by fraud; or

(ii) there was a deliberate failure to disclose material information.

(4)  An assessment or reassessment made under this section with the agreement of a taxpayer is a non-reviewable decision.