Cameco prepares its consolidated financial statements in accordance with Canadian GAAP. In doing so, management is required to make various estimates and judgments in determining the reported amounts of assets and liabilities, revenues and expenses for each year presented, and in the disclosure of commitments and contingencies. Management bases its estimates and judgments on its own experience, guidelines established by the Canadian Institute of Mining, Metallurgy and Petroleum and various other factors believed to be reasonable under the circumstances. Management believes the following critical accounting estimates reflect its more significant judgments used in the preparation of the consolidated financial statements.

Depreciation and depletion on property, plant and equipment is primarily calculated using the unit of production method. This method allocates the cost of an asset to each period based on current period production as a portion of total lifetime production or a portion of estimated recoverable ore reserves. Estimates of lifetime production and amounts of recoverable reserves are subject to judgment and significant change over time. If actual reserves prove to be significantly different than the estimates, there could be a material impact on the amounts of depreciation and depletion charged to earnings.

Significant decommissioning and reclamation activities are often not undertaken until substantial completion of the useful lives of the productive assets. Regulatory requirements and alternatives with respect to these activities are subject to change over time. A significant change to either the estimated costs or recoverable reserves may result in a material change in the amount charged to earnings. Cameco accounts for its obligations associated with the retirement of tangible long-lived assets in accordance with CICA Handbook Section 3110, Asset Retirement Obligations.

Cameco assesses the carrying values of property, plant and equipment, and goodwill annually or more frequently if warranted by a change in circumstances. If it is determined that carrying values of assets or goodwill cannot be recovered, the unrecoverable amounts are written off against current earnings. Recoverability is dependent upon assumptions and judgments regarding future prices, costs of production, sustaining capital requirements and economically recoverable ore reserves. A material change in assumptions may significantly impact the potential impairment of these assets.

Cameco uses derivative financial and commodity instruments to reduce exposure to fluctuations in foreign currency exchange rates, interest rates and commodity prices. As long as these instruments are effective, they have the effect of offsetting future changes in these underlying rates and prices. Future earnings may be adversely impacted should these instruments become ineffective.

Cameco operates in a number of tax jurisdictions and is therefore required to estimate its income taxes in each of these tax jurisdictions in preparing its consolidated financial statements. In calculating the income taxes, consideration is given to factors such as tax rates in the different jurisdictions, non-deductible expenses, valuation allowances, changes in tax laws and management's expectations of future results. Cameco estimates future income taxes based on temporary differences between the income and losses reported in its consolidated financial statements and its taxable income and losses as determined under the applicable tax laws. The tax effect of these temporary differences is recorded as future tax assets or liabilities in the consolidated financial statements. The calculation of income taxes requires the use of judgment and estimates. If these judgments and estimates prove to be inaccurate, future earnings may be materially impacted.