(1) A “tax decision” is a decision made by the Commissioner-General under a tax law, including an assessment or omission, but does not include
(a) a practice note, class ruling, or private ruling;
(b) a decision or omission to issue, refuse or revoke a practice note, class ruling or private ruling;
(c) a decision or omission that affects a person only as a tax officer or employee or agent of the Authority;
(d) a decision or omission of the Commissioner-General, including an objection decision under section 43; or
(e) a decision to compound an offence under a tax law.
(2) A tax decision is made
(a) in the case of an assessment made by the Commissioner- General, when the notice of assessment is served on the taxpayer; and
(b) in the case of any other tax decision, when the Commissioner-General serves the affected person with written notice of the decision.
(3) In the absence of the notice referred to in subsection (2)(b), a person may elect to treat the Commissioner-General as having made an unfavourable tax decision, if
(a) the tax law specifies a time by which the Commissioner-General is to make a decision and that time expires; or
(b) a time frame is not specified in the tax law and ninety days have elapsed after the affected person files a request for the Commissioner-General to make the decision.
(4) The following are conclusive evidence that a tax decision has been made and is correct:
(a) in the case of a self-assessment, the tax return that resulted in the assessment or a document under the hand of the Commissioner-General purporting to be a copy of the tax return;
(b) in the case of other assessments, the notice of assessment or a document under the hand of the Commissioner-General purporting to be a copy of the notice; and
(c) in the case of any other tax decision, written notice of the decision under the hand of the Commissioner-General or a document under the hand of the Commissioner-General purporting to be a copy of the decision.
(5) For the purpose of this section, a reference to the Commissioner-General making a decision includes the Commissioner-General exercising a discretion, making a judgement, giving a direction, expressing an opinion, granting an approval or consent, or being satisfied in respect of a matter.