18. Income and Resource Taxes (continued)  (Cdn$ in millions) 2012 2011 As at January 1  $ 5,162 $ 4,554 Income statement change  98 701 Tax charge (credit) relating to components of other comprehensive income  (10) (76) Foreign exchange and other differences  (32) (17) As at December 31  $ 5,218 $ 5,162 Deferred tax liabilities of $370 million (2011 - $367 million) have not been recognized on the unremitted earnings of  controlled subsidiaries, branches and interest in joint ventures as the timing of remittance for these earnings is in our  control and it is probable that these earnings will not be repatriated for the foreseeable future. We reduced our provision for withholding taxes by $26 million within the year based on our plans for repatriation or  reinvestment of the earnings of foreign subsidiaries. At December 31, 2012, we had $4.26 billion of Canadian federal net operating loss carry forwards (2011 - $4.74 billion).  These loss carry forwards expire at various dates between 2013 and 2031. We also had $2.56 billion of cumulative  Canadian development expenses at December 31, 2012 (2011 - $3.62 billion), which are deductible for income tax  purposes on a declining balance basis at a maximum rate of 30% per year. We have not recognized $226 million (2011 - $237 million) of deferred tax assets in jurisdictions and entities that do  not have established sources of taxable income. Subsequent to year end, the Government of British Columbia announced a 1% increase in corporate income tax rates.  If enacted, this would result in an approximately $65 million non-cash charge to earnings in respect of our existing  deferred tax liabilities. Notes to Consolidated Financial Statements  Years ended December 31, 2012 and 2011 g) Deferred Tax Liabilities Not Recognized h) Loss Carry Forwards and Canadian Development Expenses i) Deferred Tax Assets Not Recognized j) Subsequent Event f) The gross movement on the net deferred income tax account is as follows: Teck 2012 Annual Report 108