paragraphs. While fiscal years 2007 and 2008 are currently under examination by the IRS, we are not able to reasonably estimate the timing of future cash flows beyond 12 months due to uncer- tainties in the timing of this and other tax audit outcomes. Postemployment Benefit Plans Under certain circumstances, we also provide accruable benefits to former or inactive employees in the United States, Canada, and Mexico, and members of our Board of Directors, including severance and certain other benefits payable upon death. We recognize an obligation for any of these benefits that vest or accumulate with service. Postemployment benefits that do not vest or accumulate with service (such as severance based solely on annual pay rather than years of ser- vice) are charged to expense when incurred. Our postemploy- ment benefit plans are unfunded. Various tax examinations by United States state taxing author- ities could be conducted for any open tax year, which vary by jurisdiction, but are generally from 3 to 5 years. Currently, several state examinations are in progress.The Canada Revenue Agency is conducting an audit of our income tax returns in Canada for fiscal years 2003 (which is our earliest tax year still open for examina- tion) through 2005. We do not anticipate that any United States state tax or Canadian tax adjustments will have a significant impact on our financial position or results of operations. We recognize benefits provided during retirement or following employment over the plan participants’ active working life. Accordingly, we make various assumptions to predict and mea- sure costs and obligations many years prior to the settlement of our obligations. Assumptions that require significant manage- ment judgment and have a material impact on the measurement of our net periodic benefit expense or income and accumulated benefit obligations include the long-term rates of return on plan assets, the interest rates used to discount the obligations for our benefit plans, and the health care cost trend rates. Defined Benefit Pension Plans We have defined benefit pension plans covering most domestic, Canadian, and United Kingdom employees. Benefits for salaried employees are based on length of service and final average compensation. Benefits for hourly employees include various monthly amounts for each year of credited service. Our funding policy is consistent with the requirements of applicable laws. We made $200 million of voluntary contributions to our principal domestic plans in fiscal 2009. We did not make any contributions in fiscal 2010, and we do not expect to be required to make any contributions in fiscal 2011. Our principal domestic retirement plan covering salaried employees has a provision that any excess pension assets would be allocated to active participants if the plan is ter- minated within five years of a change in control. Expected Rate of Return on Plan Assets Our expected rate of return on plan assets is determined by our asset allocation, our historical long-term investment performance, our estimate of future long-term returns by asset class (using input from our actuaries, investment services, and investment managers), and long-term inflation assumptions. We review this assumption annually for each plan, however, our annual investment perfor- mance for one particular year does not, by itself, significantly influence our evaluation. Other Postretirement Benefit Plans We also sponsor plans that provide health care benefits to the majority of our domestic and Canadian retirees. The salaried health care benefit plan is con- tributory, with retiree contributions based on years of service.We make decisions to fund related trusts for certain employees and retirees on an annual basis. We did not make voluntary contri- butions to these plans in fiscal 2010. The Patient Protection and Affordable Care Act, as modified by the Health Care and Edu- cation Reconciliation Act of 2010, was enacted in March 2010.The effect of the Act, including possible modifications to provider plans, has not yet been fully evaluated, but could affect the future cost of our benefit plans. The investment objective for our defined benefit pension and other postretirement benefit plans is to secure the benefit obli- gations to participants at a reasonable cost to us. Our goal is to optimize the long-term return on plan assets at a moderate level of risk. The defined benefit pension and other postretirement portfolios are broadly diversified across asset classes. Within asset classes, the portfolios are further diversified across invest- ment styles and investment organizations. For the defined benefit pension and other postretirement benefit plans, the long-term investment policy allocations are: 30 percent to equities in the United States; 20 percent to international equities; 10 percent to private equities; 30 percent to fixed income; and 10 percent to real 39 Annual Report 2010 Defined Benefit Plans