This excerpt taken from the ELN 6-K filed Mar 30, 2009.
b Recognition of U.S. deferred tax assets
There are different rules under IFRS and U.S. GAAP in relation to the recognition of DTAs associated with share-based compensation. DTAs are only recognised under either GAAP in relation to jurisdictions where tax deductions are available to the employer for equity grants given to employees (relevant employee equity awards). For example, such tax deductions are available in the United States but in general not in Ireland. Under U.S. GAAP, a DTA may be recognised for relevant employee equity awards only to the extent that a compensation expense has previously been recorded in relation to those awards. In contrast, under IFRS, a DTA may be recognised in relation to the tax effect of the full intrinsic value at the balance sheet date of all relevant employee equity awards expected to be exercised, regardless of whether or not a compensation expense has previously been recognised for those awards. Accordingly, the total DTA recognised under IFRS is substantially higher than under U.S. GAAP. Additionally, under IFRS the amount of the DTA recorded through the income statement is limited to the tax value of the compensation expense previously recognised for those awards (similar to U.S. GAAP), with the balance between that amount and the tax effect of the total intrinsic value recorded as a credit directly to shareholders equity (IFRS only; as described above there is no equivalent DTA under U.S. GAAP). However, the amount of DTA recognised in the income statement is higher under IFRS than under U.S. GAAP because the expensing of share-based compensation commenced earlier under IFRS (November 2002) than under U.S. GAAP (January 2006), and consequently the tax value of the cumulative compensation expense is significantly higher under IFRS compared to U.S. GAAP.