This excerpt taken from the SYT 20-F filed Mar 1, 2006.
Post-employment benefit expense for 2006 will be determined based on the same discount rate, salary and pension increase, mortality, disability and employee turnover assumptions as used in valuing the benefit obligation at December 31, 2005, and on the assumed long-term expected rate on pension plan assets. These key assumptions are disclosed in Note 26 below, as are the experience variances which arose in the past five years between actual outcomes and the assumptions applied in each respective year. Assumptions are reviewed annually, and updated based on actual experience when appropriate. In this five year period, variances were caused principally by external financial market movements in the corporate bond yields used to benchmark the discount rate, and in asset prices which affected the actual return on assets. These factors are outside Syngentas direct control, and it is reasonably possible that future variances will be at least as great as past variances. Syngenta applied the corridor method, under which variances are spread prospectively over average remaining employee service. This limits the impact of variances on the reported net income and net assets of each individual accounting period. At December 31, 2005, Syngentas balance sheet included assets of US$497 million and liabilities of US$193 million and US$38 million for post-employment benefits (Note 26 below).