to earnings in the period in which we make such 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.

 

The amount of income taxes we pay is subject to ongoing audits by federal, state and foreign tax authorities, which often result in proposed assessments. Our estimate for 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 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 will not be tax deductible and will result in an increased effective income tax rate in the quarter the impairment is recorded. Amortization expense associated with acquired intangible assets is likewise not tax deductible, however deferred taxes have been recorded as part of the purchase price allocation, and therefore, will not affect our post-acquisition income tax rate. Income tax contingencies existing as of the acquisition dates of the acquired companies are evaluated quarterly, and any adjustments are recorded as an adjustment to goodwill.

 

Legal Contingencies

 

We are currently involved in various claims and legal proceedings. Quarterly, we review the status of each significant matter and assess our potential financial exposure. If the potential loss from any claim or legal proceeding is considered probable and the amount can be reasonably estimated, we accrue a liability for the estimated loss. Significant judgment is required in both the determination of probability and the determination as to whether an exposure is reasonably estimable. Because of uncertainties related to these matters, accruals are based only on the best information available at the time. As additional information becomes available, we reassess the potential liability related to our pending claims and litigation and may revise our estimates. Such revisions in the estimates of the potential liabilities could have a material impact on our results of operations and financial position.

 

Stock-Based Compensation

 

We currently measure compensation expense for our stock-based incentive programs using the intrinsic value