How are mining restoration costs capitalized?

Question

AcadiFi · Accepted Answer

Restoration costs are accounted for as asset retirement obligations (AROs) under ASC 410-20 / IFRS IAS 37. At inception, recognize a liability at the present value of expected future retirement costs, and capitalize an equivalent amount as part of the mining asset's carrying value.

Example: Tungsten Ridge Mining opens a copper mine in Chile with expected closure in 18 years. Estimated restoration cost at closure: $42M (reclamation, water treatment, revegetation). Credit-adjusted risk-free rate: 6.2%. PV = $42M / (1.062)^18 = $14.3M.

Initial entry:
- Dr. Mine Asset $14.3M
- Cr. ARO Liability $14.3M

Subsequent accounting:
- **Depreciation**: The $14.3M capitalized cost is depreciated over the mine's useful life (often units-of-production) alongside other mine development costs.
- **Accretion**: Each period, accretion expense = opening ARO × 6.2%. Year 1: $14.3M × 6.2% = $0.89M. The ARO liability grows toward $42M at closure.

Accretion is an operating expense (not interest) under US GAAP but can be treated as financing under IFRS. At closure, actual restoration payments are debited against the ARO; any difference from the settled amount is a gain or loss.

The initial discount rate is locked in for upward revisions of existing obligations but current rates apply to downward revisions — a quirk of ASC 410-20.

How are mining restoration costs capitalized?

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