1.  Same as federal.  For purposes of the tax imposed by this Part, a taxpayer's method of accounting must be the same as that taxpayer's method of accounting for federal income tax purposes. If no method of accounting has been regularly used by the taxpayer, taxable income for purposes of this Part must be computed under a method that in the opinion of the assessor fairly reflects income.  

2.  Change of accounting methods.  If a taxpayer's method of accounting is changed for federal income tax purposes, that taxpayer's method of accounting for purposes of this Part must similarly be changed.