(1)  If a taxpayer's objection to an assessment is allowed in whole or in part, the decision of the Commissioner is not affirmed on review or a taxpayer's review or appeal is upheld, the Commissioner must –

(a) refund any amount paid in excess of a requirement for payment; or

(b) apply the amount paid in excess of a requirement for payment against any liability of the person under a taxation law, or another Act of which the Commissioner has the general administration, and refund any part of the amount paid in excess that is not so applied.

(2)  If a taxpayer's objection to a decision other than an assessment is allowed in whole or in part, the decision of the Commissioner is not affirmed on review or a taxpayer's review or appeal is upheld, the Commissioner must –

(a) refund any amount paid in the relevant period in excess of a requirement for payment; or

(b) apply the amount paid in the relevant period in excess of a requirement for payment against any liability of the person under a taxation law, or another Act of which the Commissioner has the general administration, and refund any part of the amount paid in excess that is not so applied.

(3)  A relevant period for the purpose of subsection (2) is a period of 5 years immediately preceding the earlier of the following:

(a) the date of the decision;

(b) if the decision was made in response to a written request from the taxpayer that included a description of the facts and circumstances on which the request was based, the date of the request for the decision.