The net income shall be determined in accordance with the accounting basis employed by the taxpayer, whether it be a fiscal year or a calendar year and in accordance with the method of accounting employed whether it be cash or accrual. The accounting method used by a taxpayer must clearly reflect income and expenses. The taxpayer's method of accounting must be consistent; no method of accounting is regarded as clearly reflecting income unless all items of gross profit and deduction are treated with consistency from year to year.
35 Miss. Code. R. 3-01-03-104