(a) Companies shall apply interperiod tax allocation (tax normalization) to all book/tax temporary differences which would be considered material for published financial report purposes. Furthermore, companies shall also apply interperiod tax allocation if any item or group of similar items when aggregated would yield debit or credit entries which exceed or would exceed 5 percent of the gross deferred income tax expense debits or credits during any calendar year over the life of the temporary difference. The tax effects of book/tax temporary differences shall be normalized and the deferrals shall be included in the following accounts: 4100, Net Current Deferred Operating Income Taxes;
4110, Net Current Deferred Nonoperating Income Taxes;
4340, Net Noncurrent Deferred Operating Income Taxes;
4350, Net Noncurrent Deferred Nonoperating Income Taxes.
In lieu of the accounting prescribed herein, any company shall treat the increase or reduction in current income taxes payable resulting from the use of flow through accounting in prior years as an increase or reduction in current tax expense.