Total interest expense increased $130,000, or 79.3%, to $294,000 for the three months ended September 30, 2022 compared to $164,000 for the three months ended September 30, 2021 due to an increase in the average balance of interest-bearing liabilities and an increase in the cost of borrowings. The average balance of interest-bearing liabilities increased to $204.3 million for the quarter ended September 30, 2022 from $174.6 million for the same period in 2021, due primarily to increases in savings and interest-bearing demand deposit accounts, time deposits and FHLB borrowings. The average cost of interest-bearing liabilities increased to 0.57% for the quarter ended September 30, 2022 from 0.38% for the same period in 2021. The average cost of deposits remained at 0.29% for the quarters ended September 30, 2022 and 2021. As a result of the changes in interest-earning assets and interest-bearing liabilities, the interest rate spread and interest rate spread on a tax-equivalent basis(1) increased to 2.85% and 3.02%, respectively, for the quarter ended September 30, 2022, from 2.81% and 2.99%, respectively, for the quarter ended September 30, 2021. The net interest margin and the net interest margin on a tax-equivalent basis(1) increased to 2.99% and 3.16%, respectively, for the quarter ended September 30, 2022 from 2.92% and 3.09%, respectively, for the quarter ended September 30, 2021.
Net interest income after provision for loan losses increased $436,000, or 8.5%, to $5.6 million for the nine months ended September 30, 2022 compared to $5.1 million for the nine months ended September 30, 2021 due primarily to an increase in the average balance of interest-earning assets and an increase in the yield earned on interest-earning assets, partially offset by an increase in the average balance of interest-earning liabilities, an increase in the cost of interest-bearing liabilities and increased provision for loan losses.
Total interest income was $6.3 million for the nine months ended September 30, 2022 compared to $5.6 million for the nine months ended September 30, 2021. Interest income from loans receivable increased $439,000, while interest income from investment securities increased $217,000 and interest income from interest-bearing deposits with banks increased $14,000. The average balance of interest-earning assets increased to $260.4 million for the nine months ended September 30, 2022 from $235.0 million for the nine months ended September 30, 2021, due primarily to increases in loans receivable and investment securities, partially offset by decreases in interest-bearing deposits with banks. The average yield on interest-earning assets and average tax-equivalent yield on interest-earning assets(1) increased to 3.24% and 3.41%, respectively, for the nine months ended September 30, 2022 from 3.20% and 3.38%, respectively, for the nine months ended September 30, 2021, due primarily to changes in the investment asset mix.
Total interest expense increased $116,000, or 23.2%, to $617,000 for the nine months ended September 30, 2022 compared to $501,000 for the nine months ended September 30, 2021 due to increases in both the average cost and balance of interest-bearing liabilities. The average cost of interest-bearing liabilities increased to 0.42% for the nine months ended September 30, 2022 from 0.39% for the same period in 2021. The average balance of interest-bearing liabilities increased to $195.4 million for the nine months ended September 30, 2022 from $169.9 million for the same period in 2021, due primarily to an increase in savings and interest-bearing demand deposits and higher FHLB borrowings, partially offset by a decrease in time deposits. The average cost of deposits decreased to 0.26% for the nine months ended September 30, 2022 from 0.31% for the same period in 2021. As a result of the changes in interest-earning assets and interest-bearing liabilities, the interest rate spread and interest rate spread on a tax-equivalent basis(1) was 2.82% and 2.99%, respectively, for the nine months ended September 30, 2022. The net interest margin and the net interest margin on a tax-equivalent basis(1) increased to 2.93% and 3.10%, respectively, for the nine months ended September 30, 2022 from 2.92% and 3.09%, respectively, for the nine-month period ended September 30, 2021.
Provision for Loan Losses. Non-performing loans increased to $857,000, at September 30, 2022 compared to $753,000 at December 31, 2021, or 0.6% of total loans for both periods. At September 30, 2022, $576,000 or 67.2% of nonperforming loans were current on their loan payments. Based on an analysis of the factors described in "Summary of Significant Accounting Policies – Allowance for Loan Losses,” the Company recorded a provision for loan losses of $85,000 and $135,000 for the three and nine months ended September 30, 2022, respectively, compared to no provision for the same periods of 2021.
Noninterest Income. Noninterest income decreased $6,000, or 2.0%, for the quarter ended September 30, 2022 as compared to the same period in 2021, due primarily to a reduction in brokered loan fees of $23,000, partially offset by increases of $13,000 and $6,000 in deposit account service charges and ATM and debit card fee income, respectively.