Non-compensation operating expenses, presented on a comparable basis excluding reimbursable client expenses and the remeasurement of the Cogent earnout, would have been $49.1 million for the nine months ended September 30, 2018 as compared to $53.9 million for the same period in 2017. This decrease of $4.8 million principally related to lower travel expenses, a smaller foreign currency loss on our foreign operations and the absence of charges for uncollectible accounts, offset by higher professional fees and occupancy expenses.
Ournon-compensation operating expenses can vary as a result of a variety of factors such as changes in headcount, the amount of recruiting and business development activity, the amount of office expansion, the amount of client reimbursed expenses, costs associated with acquisitions, the impact of currency movements and other factors, such as the contingent earnout. Accordingly, thenon-compensation operating expenses in any particular period may not be indicative of thenon-compensation operating expenses in future periods.
Interest Expense
For the three months ended September 30, 2018, we incurred interest expense of $5.7 million as compared to $0.9 million for the same period in 2017. For the nine months ended September 30, 2018, we incurred interest expense of $16.6 million as compared to $2.5 million for the comparable period in 2017. The increase in interest expense during 2018 relates to borrowings under our new secured term loan facility, which was drawn down in October 2017 as part of the recapitalization plan we announced in September 2017.
The rate of interest on our borrowing is based on LIBOR and can vary from period to period. Accordingly, the amount of interest expense in any particular period may not be indicative of the amount of interest expense in future periods. Further, we are required under the term loan facility to make quarterly amortization payments and, beginning in 2019, if applicable, an annual prepayment based on a calculation of our excess cash flow.
Provision for Income Taxes
For the third quarter of 2018, the provision for income taxes was $3.8 million, reflecting an effective rate of 25%, as compared to an income tax benefit for the third quarter of 2017 of $4.4 million. Our effective tax rate in 2018 is lower than in prior periods principally as a result of the Tax Cuts and Jobs Act (the “Tax Act”), which reduced the U.S. federal corporate tax rate from 35% to 21% effective January 1, 2018.
For the nine months ended September 30, 2018, the provision for income taxes was $14.5 million, reflecting an effective rate of 34%, as compared to a provision for income taxes of $1.9 million for the same period in 2017. The provision for income taxes for the first nine months of 2018 and 2017 included charges of $4.3 million and $1.1 million, respectively, related to the tax effect of the difference between the grant price value and the market price value of restricted stock awards at the time of the vesting. Excluding these charges, the provisions for income taxes for the nine months ended September 30, 2018 and 2017 would have been $10.2 million, reflecting an effective tax rate of 24%, and $0.8 million, reflecting an effective tax rate of 54%, respectively. The decrease in the effective tax rate in the first nine months of 2018, excluding the charge related to the vesting of restricted stock awards, principally related to the Tax Act described above.
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