Income before income taxes for the year ended December 31, 2018 increased over 2017 by $12.7 million, primarily as a result of net new business and acquisitions completed in the past twelve months offset by lower weather related claims processing revenues in 2018 and a legal settlement recorded in the first quarter of 2017.
Investment income increased to $2.7 million in 2018, compared with $1.6 million in 2017 and increased to $1.6 million in 2017, compared with $1.5 million in 2016. The increases in both years were due to additional interest income driven by higher interest rates and cash management activities to earn a higher yield on excess cash balances.
Accounting Standards Codification (“ASC”) Topic 805-Business Combinations is the authoritative guidance requiring an acquirer to recognize 100% of the fair value of acquired assets, including goodwill, and assumed liabilities (with only limited exceptions) upon initially obtaining control of an acquired entity. Additionally, the fair value of contingent consideration arrangements (such as earn-out purchase price arrangements) at the acquisition date must be included in the purchase price consideration. As a result, the recorded purchase prices for all acquisitions consummated after January 1, 2009 include an estimation of the fair value of liabilities associated with any potential earn-out provisions. Subsequent changes in these earn-out obligations are required to be recorded in the Consolidated Statement of Income when incurred or reasonably estimated. Estimations of potential earn-out obligations are typically based upon future earnings of the acquired operations or entities, usually for periods ranging from one to three years.
The $52.7 million adjustment to other current assets reflects the deferral of certain cost to fulfill contracts. The $12.1 million adjustment to premiums payable to insurance companies reflects the estimated amount payable to outside brokers on unbilled premiums, commissions and fees receivable. The $8.7 million adjustment to accounts payable and the $22.8 million adjustment to accrued expenses and other liabilities consists of commissions payable and deferred revenue, respectively.
Fee revenues relate to fees for services other than securing coverage for our customers and fees negotiated in lieu of commissions.
Amortization expense for amortizable intangible assets for the years ending December 31, 2019, 2020, 2021, 2022 and 2023 is estimated to be $100.4 million, $93.0 million, $89.5 million, $85.0 million and $78.0 million, respectively.
Proceeds from the sales and maturity of the Company’s investment in fixed maturity securities were $17.1 million. This along with maturing time deposits yielded total cash proceeds from the sale of investments of $17.9 million in the period of January 1, 2018 to December 31, 2018. These proceeds were used to purchase an additional $9.3 million of fixed maturity securities and to fund certain general corporate purposes. The gains and losses realized on those sales for the period from January 1, 2018 to December 31, 2018 were insignificant.
Accrued expenses and other liabilities at December 31 consisted of the following:
For 2017, we made a reasonable estimate of the impact of the Tax Reform Act and recorded a one-time credit in our 2017 income tax expense of $120.9 million, which reflects an estimated reduction in our deferred income tax liabilities of $124.2 million as a result of the maximum federal rate decreasing to 21.0% from 35.0%, which was partially offset by an estimated increase in income tax payable in the amount of $3.3 million as a result of the transition tax on cash and cash equivalent balances related to untaxed accumulated earnings associated with our international operations. During 2018, we made a credit adjustment to the transition tax on untaxed international operations in the amount of $1.6 million. This adjustment was a reduction of income tax expense for 2018 as a result of updated calculations based on the Company’s tax filings for the 2017 year end. As of December 31, 2018, management does not expect any further changes to the amounts previously recorded and adjusted under SAB 118.
A summary of PSP activity for the years ended December 31, 2018, 2017 and 2016 is as follows:
these matters are continuing to develop, it is possible that future results of operations or cash flows for any particular quarterly or annual period could be materially affected by unfavorable resolutions of these matters. Based upon the AM Best Company ratings of these third-party insurers, management does not believe there is a substantial risk of an insurer’s material non-performance related to any current insured claims.