particular Equipment Finance origination vintage tocharge-off generally follow a pattern of lower losses for the first few months, followed by increased losses in subsequent months, then lower losses during the later periods of the lease term. Therefore, the seasoning, or mix of origination vintages, of the portfolio affects the timing and amount of anticipated probable and estimable credit losses.
The provision for credit losses for the Equipment Finance and TFG portfolios decreased by $0.4 million and $0.6, respectively, for the three-month period ending September 30, 2018 and were offset by an increase of $0.2 million in provision for Funding Stream for the same period.
Total portfolio net charge-offs were $4.5 million for the three-month period ended September 30, 2018, compared to $3.7 million for the corresponding period in 2017. The increase incharge-off rate is primarily due to the ongoing seasoning of the Equipment Finance portfolio as reflected in the mix of origination vintages and the mix of credit profiles. Total portfolio net charge-offs as an annualized percentage of average total finance receivables increased to 1.90% during the three-month period ended September 30, 2018, from 1.73% for the corresponding period in 2017. The allowance for credit losses increased to approximately $15.9 million at September 30, 2018, an increase of $1.0 million from $14.9 million at December 31, 2017.
Additional information regarding asset quality is included herein in the section “Finance Receivables and Asset Quality.”
Provision for income taxes.Income tax expense of $1.7 million and $2.0 million was recorded for the three-month periods ended September 30, 2018 and September 30, 2017, respectively. Our effective tax rate, which is a combination of federal and state income tax rates, was approximately 22.6% and 38.3% for the three-month periods ended September 30, 2018 and September 30, 2017, respectively. The decline in effective tax rate was driven by the changes in corporate tax rates from the Tax Cut and Jobs Act. As a result of these changes, the Company’s Federal Statutory rate declined from 35% to 21%.
Comparison of the Nine-Month Periods Ended September 30, 2018 and September 30, 2017
Net income. Net income of $18.6 million was reported for the nine-month period ended September 30, 2018, resulting in diluted EPS of $1.49, compared to net income of $9.4 million and diluted EPS of $0.75 for the nine-month period ended September 30, 2017. This increase was primarily due to an increase in net interest and fee margin of $4.2 million on a larger portfolio and an increase innon-interest income of $2.9 million.
Return on average assets was 2.27% for the nine-month period ended September 30, 2018, compared to a return of 1.31% for the nine-month period ended September 30, 2017. Return on average equity was 13.31% for the nine-month period ended September 30, 2018, compared to a return of 7.66% for the nine-month period ended September 30, 2017.
Overall, our average net investment in total finance receivables for the nine-month period ended September 30, 2018 increased 12.5% to $935.9 million, compared to $831.7 million for the nine-month period ended September 30, 2017. This change was primarily due to origination volume continuing to exceed lease repayments. Theend-of-period net investment in total finance receivables at September 30, 2018 was $970.4 million, an increase of $56.0 million, or 6.1%, from $914.4 million at December 31, 2017.
During the nine months ended September 30, 2018, we generated 23,605 new leases with equipment cost of $450.5 million, compared to 22,336 new leases with equipment cost of $407.0 million generated for the nine months ended September 30, 2017. Approval rates remained at 56% for the nine-month period ended September 30, 2018, compared to 56% for the nine-month period ended September 30, 2017.
For the nine-month period ended September 30, 2018 compared to the nine-month period ended September 30, 2017, net interest and fee income increased $4.2 million, or 6.2%, primarily due to a $7.6 million increase in interest income, partially offset by a $2.2 million increase in interest expense. The provision for credit losses decreased $0.1 million, or 0.7%, to $13.8 million for the nine-month period ended September 30, 2018 from $13.9 million for the same period in 2017, due to an increase in delinquency and charge-offs which is attributed to a return to a more normal credit environment.
Average balances and net interest margin.The following table summarizes the Company’s average balances, interest income, interest expense and average yields and rates on major categories of interest-earning assets and interest-bearing liabilities for the nine-month periods ended September 30, 2018 and September 30, 2017.
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