(1) An employer may, not later than the date on which an instalment of tax in respect of a year of tax is due and payable or within such further period as the Commissioner allows:
(a) make an estimate of the amount of the tax (if any) that will be payable by the employer in respect of that year of tax; and
(b) furnish to the Commissioner a written statement, in the approved form, showing:
(i) the amount so estimated; and
(ii) the basis on which the estimate has been made;
unless the employer has previously furnished a statement under this subsection in relation to the instalment of tax.
(2) Where an employer furnishes to the Commissioner, in relation to an instalment of tax, a statement under subsection (1), the estimated tax is, subject to subsection (3), an amount equal to the employer's estimate.
(3) Where, having regard to information in returns furnished by the employer and any other information in the Commissioner's possession, the Commissioner has reason to believe that the amount of tax that will be payable by the employer in respect of the year of tax is greater than the employer's estimate:
(a) the Commissioner may estimate the amount that, in the Commissioner's opinion, should have been the amount estimated by the employer pursuant to subsection (1) in respect of that year of tax; and
(b) the estimated tax is:
(i) an amount equal to the amount of tax so estimated by the Commissioner; or
(ii) the amount that would be the notional tax amount of the employer in respect of the year of tax if the employer had not furnished a statement under subsection (1);
whichever is the less.