Company: RTNTF
Filing Date: 2025-02-20
Form Type: 20-F
Source: 0001628280-25-006642
Chunk: 284

Company: RIO TINTO LTD
Filing Date: 2025-02-20
Form: 20-F
Chunk 284
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13)                            |    a |    a | The useful lives of major assets are often linked to the life of the orebody theyrelate to, which is in turn based on the life-of-mine plan. Where the majorassets are not dependent on the life of a related orebody, management appliesjudgement in estimating the remaining service potential of long-lived assets.The accuracy of estimating these useful lives is essential for determining theappropriate allocation of costs over time, reflecting the consumption of theasset’s economic benefits.    |
| Close-down, restoration andenvironmental obligations (note 14) |    a |    a | Significant judgement is required to assess the possible extent of closurerehabilitation work needed to fulfil the Group’s legal, statutory, and constructiveobligations, along with other commitments to stakeholders. This involvesleveraging our experience in evaluating available options and techniques tomeet these obligations, associated costs and their likely timing and, crucially,determining when that estimate is sufficiently reliable to make or adjust aclosure provision.                 |

| Annual Report on Form 20-F 2024 | 156 | riotinto.com |

Financial statements

e. Key sources of estimation uncertainty

We define key sources of estimation uncertainty as accounting estimates that have a significant risk of causing a material adjustment to the

carrying amounts of assets and liabilities within the next financial year. We summarise below the most significant items and the rationale for their

identification. Relevant sensitivities are included within the indicated financial statement notes.

| Key accounting estimates                                                             | 2024 | 2023 | Context                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Estimation of the close-down, restorationand environmental costobligations (note 14) |    a |    a | Close-down, restoration and environmental obligations are based on cash flow projections derived fromstudies that incorporate planned rehabilitation activities, cost estimates and discounting for the timevalue. Closure studies are performed to a rolling schedule with increased frequency and engineeringaccuracy for sites approaching end of life. Information from these studies can result in a material changeto the associated provisions. During the year, the most significant closure provision updates related to anumber of sites across the Pilbara. The provisions are based on reforecast cash flows, these are subjectto further study which could result in material adjustment in the near term. |
| Estimation of obligations forpost-employment costs(note 28)                          |    a |    a | The value of the Group’s obligations for post-employment benefits is dependent on the amount