originated in the three months ended September 30, 2020 compared to the three months ended September 30, 2019. The increase in the number of new loans originated resulted in an increase in loan capitalization and an offset to salary expense for the three months ended September 30, 2020. The decrease in employee stock ownership plan expense is primarily due to a decline in our stock price, which is used to calculate this expense. The decrease in other general and administrative expenses was primarily due to decreases in advertising expense and accounting and auditing expenses. The decrease in federal deposit insurance premiums was due to a credit received in the three months ended September 30, 2019 because the FDIC insurance fund was over-capitalized. The increase in equipment expense was primarily due to an increase in service bureau expense.
Income Tax Expense. Income taxes were $1.6 million for the three months ended September 30, 2020, reflecting an effective tax rate of 27.6%, compared to $1.8 million for the three months ended September 30, 2019, reflecting an effective tax rate of 24.9%. Income tax expense for the three months ended September 30, 2019 included tax benefits of $34,000 related to the exercise of stock options. The increase in the effective tax rate for the three months ended September 30, 2020 is also attributed to an increase in income tax expense related to executive compensation plans.
Comparison of Operating Results for the Nine Months Ended September 30, 2020 and 2019
General. Net income decreased by $3.9 million, or 22.8%, from $17.0 million for the nine months ended September 30, 2019 to $13.1 million for the nine months ended September 30, 2020. The decrease in net income was due to a $2.5 million decrease in noninterest income, a $2.2 million increase in loan loss provisions and a $302,000 decrease in net interest income. These decreases in net income were partially offset by a $791,000 decrease in noninterest expense and a $358,000 decrease in income tax expense.
Net Interest Income. Net interest income decreased by $302,000, or 0.7%, to $43.7 million for the nine months ended September 30, 2020 from $44.0 million for the nine months ended September 30, 2019. Interest income decreased by $3.1 million, or 5.4%, due to a 23 basis point decrease in the average yield of interest-earning assets, which was partially offset by a $15.8 million increase in the average balance of interest-earning assets. Interest expense decreased by $2.7 million, or 21.6%, due to a 22 basis point decrease in the cost of average interest-bearing liabilities, which was partially offset by a $8.3 million increase in the average balance of interest-bearing liabilities. The interest rate spread and net interest margin were 2.80% and 2.90% respectively, for the nine months ended September 30, 2020, compared to 2.81% and 2.94%, respectively, for the nine months ended September 30, 2019. The decreases in the interest rate spread and in the net interest margin are attributable to the 23 basis point decrease in the yield on average interest-bearing assets that was partially offset by the 22 basis point decrease in the cost of average interest-earning liabilities.
Interest Income. Interest income decreased by $3.1 million, or 5.4%, to $53.7 million for the nine months ended September 30, 2020 from $56.8 million for the nine months ended September 30, 2019. Interest income on loans decreased by $2.2 million, or 4.6%, to $45.3 million for the nine months ended September 30, 2020 from $47.5 million for the nine months ended September 30, 2019. The decrease in interest income on loans occurred because the average balance of loans decreased by $39.9 million, or 2.5%, and the average loan yield decreased by nine basis points. The decrease in the average balance occurred as loan repayments, loan sales and loan securitizations exceeded new loan originations. Interest income on securities decreased by $929,000, or 10.8%, to $7.7 million for the nine months ended September 30, 2020 from $8.6 million for the nine months ended September 30, 2019. The decrease in interest income on securities occurred because the average balance of securities decreased by $23.8 million, or 6.4%, as security repayments and sales exceeded security purchases and loan securitizations. The decrease in interest income on securities was augmented by a 14 basis point decrease in the average yield on securities, which occurred as higher yielding securities were paid off or sold.
Interest Expense. Interest expense decreased by $2.7 million, or 21.6%, to $10.0 million for the nine months ended September 30, 2020 from $12.7 million for the nine months ended September 30, 2019. Interest expense on interest-bearing deposits decreased by $2.7 million, or 27.0%, from $10.1 million for the nine months ended September 30, 2019 to $7.4 million for the nine months ended September 30, 2020. The decrease in interest expense on interest-bearing deposits was due to a 23 basis point decrease in the average rate paid on interest-bearing deposits and a $3.3