The provision for deferred income taxes arises from temporary differences in the carrying values of assets and liabilities for financial statement and income tax purposes and the effect of loss carry forwards. The items comprising the deferred income tax assets and liabilities are as follows: In 2020, the Company revalued its deferred income tax balances as a result of a tax filing election for the state of North Dakota resulting in a lower corporate income tax rate and a net recovery of $ 29 million . In 2019, the Company revalued its deferred income tax balances as a result of a corporate income tax rate decrease in the province of Alberta, resulting in a net recovery of  $88 million . In 2018, the Company revalued its deferred income tax balances as a result of corporate income tax rate decreases in the states of Iowa and Missouri, resulting in a net recovery of  $21 million . The Company has not provided a deferred liability for the income taxes, if any, which might become payable on any temporary difference associated with its foreign investments because the Company intends to indefinitely reinvest in its foreign investments and has no intention to realize this difference by a sale of its interest in foreign investments. It is not practical to calculate the amount of the deferred tax liability. It is more likely than not that the Company will realize the majority of its deferred income tax assets from the generation of future taxable income, as the payments for provisions, reserves and accruals are made and losses and tax credits carried forward are utilized. The Company’s consolidated effective income tax rate differs from the expected Canadian statutory tax rates. Expected income tax expense at statutory rates is reconciled to income tax expense as follows: (in millions of Canadian dollars) 2020 2019 Deferred income tax assets Amount related to tax losses carried forward $ 17 $ 6  Liabilities carrying value in excess of tax basis 131 139  Unrealized foreign exchange losses 4 26  Environmental remediation costs 22 22  Other 4 4  Total net deferred income tax assets 178 197  Deferred income tax liabilities Properties carrying value in excess of tax basis 3,708 3,524  Pensions carrying value in excess of tax basis 43 83  Other 93 91  Total deferred income tax liabilities 3,844 3,698  Total net deferred income tax liabilities $ 3,666 $ 3,501  (in millions of Canadian dollars, except percentage) 2020 2019 2018 Statutory federal and provincial income tax rate (Canada) 26.31 % 26.77  % 26.86  % Expected income tax expense at Canadian enacted statutory tax rates $ 842 $ 842  $ 695  (Decrease) increase in taxes resulting from: (Gains) losses not subject to tax (23) (19) 8  Canadian tax rate differentials (3) —  —  Foreign tax rate differentials (32) (33) (55) Effect of tax rate decrease (32) (95) (21) Valuation allowance — (5) 5  Unrecognized tax benefits (7) 33  —  Other 13 (17) 5  Income tax expense $ 758 $ 706  $ 637  93 CP 2020 ANNUAL REPORT