(1) Taxpayers who use the annualization option in estimating their current year tax must accurately determine the amount of income and deductions for each installment period.

(2) Income or expenses that are paid occasionally during a year cannot be spread out during the year in determining the required installments. For example, a taxpayer who distributes year-end bonuses to employees but does not determine the amount of the bonuses until the last month of the tax year may not deduct any portion of such year-end bonuses in determining taxable income for any installment period other than the final installment period for the tax year, since deductions are not allowable until paid or accrued, depending on the taxpayer's method of accounting.