At December 31, 2010, the U.S. subsidiaries had accumulated net operating losses and deferred interest deductions  available for carryforward for income tax purposes of approximately $113,158 (2009 - $105,838). The losses expire  between 2018 and 2030. The deferred interest deductions do not generally expire. The net future tax assets of these  corporate subsidiaries of $50,221 (2009 - $54,204) consist of net operating losses, deferred interest deductions and tax  and book basis differences relating to U.S. income properties and accrued rent receivable against which a valuation  allowance of $50,221 (2009 - $54,204) has been recorded.  The SIFT tax effects of temporary differences that give rise to significant portions of the future income tax assets and  liabilities in 2009 are as follows:  In respect of assets and liabilities of the REIT, its subsidiary trust and flow through entities, the net book value for  accounting purposes of those net assets exceeds their tax basis by an amount of approximately $515,000 (2009 -  $521,000).  23.  Income tax recovery (continued): 37  2009  Future income tax liabilities: Income properties 98,875 $ Properties under dev elopment 10,812 Accrued rent receiv able 26,839 Mortgages receiv able 181 Mortgages pay able - Other assets 1,415 138,122 Future income tax assets: Intangible liabilities 10,480 Deferred ex penses 2,408 Issue costs 1,147 Mortgages pay able 281 14,316 Net future income tax liability 123,806 $ H&R REAL ESTATE INVESTMENT TRUST  H&R FINANCE TRUST  Notes to Combined Financial Statements   (In thousands of dollars, except unit and per unit amounts)  Years ended December 31, 2010 and 2009 