4 Changes in the measurement of an existing decommissioning, restoration and similar liability that result from changes in the estimated timing or amount of the outflow of resources embodying economic benefits required to settle the obligation, or a change in the discount rate, shall be accounted for in accordance with paragraphs 5-7 below.

5 If the related asset is measured using the cost model:

(a) subject to (b), changes in the liability shall be added to, or deducted from, the cost of the related asset in the current period.

(b) the amount deducted from the cost of the asset shall not exceed its carrying amount. If a decrease in the liability exceeds the carrying amount of the asset, the excess shall be recognised immediately in profit or loss.

(c) if the adjustment results in an addition to the cost of an asset, the entity shall consider whether this is an indication that the new carrying amount of the asset may not be fully recoverable. If it is such an indication, the entity shall test the asset for impairment by estimating its recoverable amount, and shall account for any impairment loss, in accordance with IAS 36.

6 If the related asset is measured using the revaluation model:

(a) changes in the liability alter the revaluation surplus or deficit previously recognised on that asset, so that: