tax rate.

 

We record a valuation allowance to reduce our deferred tax assets to the amount that is more likely than not to be realized. In order for us to realize our deferred tax assets, we must be able to generate sufficient taxable income in those jurisdictions where the deferred tax assets are located. We consider future growth, forecasted earnings, future taxable income, the mix of earnings in the jurisdictions in which we operate and prudent and feasible tax planning strategies in determining the need for a valuation allowance. In the event we were to determine that we would not be able to realize all or part of our net deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to earnings in the period in which we make such a determination. Likewise, if we later determine that it is more likely than not that the net deferred tax assets would be realized, we would reverse the applicable portion of the previously provided valuation allowance.

 

We calculate our current and deferred tax provision based on estimates and assumptions that could differ from the actual results reflected in income tax returns filed during the subsequent year. Adjustments based on filed returns are generally recorded in the period when the tax returns are filed and the global tax implications are known, which can materially impact our effective tax rate.

 

The amount of income tax we pay is subject to ongoing audits by federal, state and foreign tax authorities, which often result in proposed assessments. Our estimate of the potential outcome for any uncertain tax issue is highly judgmental. We believe we have adequately provided for any reasonably foreseeable outcome related to these matters. However, our future results may include favorable or unfavorable adjustments to our estimated tax liabilities in the period the assessments are made or resolved, audits are closed or when statutes of limitation on potential assessments expire. Additionally, the jurisdictions in which our earnings or deductions are realized may differ from our current estimates. As a result, our effective tax rate may fluctuate significantly on a quarterly basis.

 

As part of our accounting for business combinations, some of the purchase price is allocated to goodwill and intangible assets. Impairment charges associated with goodwill are generally not tax deductible and will result in an increased effective income tax rate in the quarter any impairment is recorded. Amortization expenses associated with acquired intangible assets are generally not tax deductible pursuant to our existing tax structure; however, deferred taxes have been recorded for non-deductible amortization expenses as a part of the purchase price allocation process. We have taken into account the allocation of these identified intangibles among different taxing jurisdictions, including those with nominal or zero percent tax rates, in establishing the related deferred tax liabilities. Income tax contingencies existing as of the acquisition dates of the acquired companies are evaluated quarterly and any adjustments are recorded as adjustments to goodwill.

 

On June 1, 2007, we