If a person does not file a federal income tax return, the person shall compute Maryland taxable income in accordance with the cash or accrual accounting method that: the person uses to compute income regularly in keeping the person’s books; or the Comptroller requires to reflect clearly the person’s income. If a person does not file a federal income tax return, the person shall compute Maryland taxable income: for the calendar year; or if the person keeps adequate records for an annual fiscal year accounting period, for the fiscal year.