Our acquisitions may include contingent consideration as part of the purchase price under which we will make future payments to the seller upon the achievement of certain benchmarks. The fair value of the contingent consideration is estimated as of the acquisition date at the present value of the expected contingent payments to be made using a probability-weighted discounted cash flow model for probabilities of possible future payments. The present value of the expected future payouts is accreted to interest expense over the period. The fair value estimates use unobservable inputs that reflect our own assumptions as to the ability of the acquired business to meet the targeted benchmarks and discount rates used in the calculations. The unobservable inputs are defined in FASB ASC Topic 820, “ as Level 3 inputs discussed in detail in Note 14.

We review the probabilities of possible future payments to the estimated fair value of any contingent consideration on a quarterly basis over the period. Actual results are compared to the estimates and probabilities of achievement used in our forecasts. Should actual results of the acquired business increase or decrease as compared to our estimates and assumptions, the estimated fair value of the contingent consideration liability will increase or decrease, up to the contracted limit, as applicable. Changes in the estimated fair value of the contingent consideration are reflected in our results of operations in the period in which they are identified. Changes in the estimated fair value of the contingent consideration may materially impact and cause volatility in our operating results.