Total interest income was $5.6 million for both the nine months ended September 30, 2021 and September 30, 2020. While total interest income was essentially flat for the period, interest income from investment securities increased $445,000, partially offset by a $316,000 decrease in interest income from loans receivable and a $56,000 decrease in interest income from interest-bearing deposits with banks. The average balance of interest-earning assets increased to $235.0 million for the nine months ended September 30, 2021 from $204.7 million for the nine months ended September 30, 2020, due primarily to increases in investment securities, partially offset by decreases in loans receivable and interest-bearing deposits with banks. The average tax equivalent yield on interest-earning assets declined to 3.38% for the nine months ended September 30, 2021 from 3.78% for the nine months ended September 30, 2020, due primarily to a decrease in market interest rates.
Total interest expense decreased $237,000, or 32.1%, to $501,000 for the nine months ended September 30, 2021 compared to $738,000 for the nine months ended September 30, 2020 due to a decrease in the average cost of interest-bearing liabilities, partially offset by an increase in the average balance of interest-bearing liabilities. The average cost of interest-bearing liabilities decreased to 0.39% for the nine months ended September 30, 2021 from 0.69% for the same period in 2020. The average balance of interest-bearing liabilities increased to $169.9 million for the nine months ended September 30, 2021 from $142.1 million for the same period in 2020, due primarily to an increase in the number and balance of savings and interest-bearing demand deposit accounts, partially offset by a decrease in time deposits. The average cost of deposits decreased to 0.31% for the nine months ended September 30, 2021 from 0.61% for the same period in 2020. As a result of the changes in interest-earning assets and interest-bearing liabilities, the interest rate spread decreased to 2.99% from 3.09% and the net interest margin decreased to 3.09% from 3.29% for the nine-month periods ended September 30, 2021 and 2020, respectively.
Provision for Loan Losses. Non-performing loans decreased to $650,000, at September 30, 2021 compared to $1.3 million at December 31, 2020, or 0.5% and 1.1% of total loans, respectively. At September 30, 2021, $422,000 or 65.0% 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 did not record a provision for loan losses for the three months ended September 30, 2021, compared to a $30,000 provision for loan losses for the same period of 2020. For the nine months ended September 30, 2021, the Company did not record a provision for loan losses while it recorded a $102,000 provision for the same period in 2020. We believe the provision for loan losses could increase in future periods based on the possibility of increased loan delinquencies and defaults as a result of the COVID-19 pandemic.
Noninterest Income. Noninterest income increased $99,000, or 49.0%, for the quarter ended September 30, 2021 as compared to the same period in 2020, due primarily to increases of $42,000, $28,000, and $28,000 in deposit account service charges, brokered loan fees and ATM and debit card fee income, respectively.
Noninterest income increased $243,000, or 37.0%, for the nine months ended September 30, 2021 as compared to the same period in 2020, due primarily to increases of $164,000, $100,000, and $80,000 in brokered loan fees, ATM and debit card fee income and deposit account service charges, respectively, partially offset by a reduction of $104,000 in net gain on sales of securities available for sale. Proceeds from sales of securities available for sale were $4.5 million for the nine months ended September 30, 2020. No available for sale securities have been sold during the nine months ended September 30, 2021.
Noninterest Expense. Noninterest expense increased $25,000, or 1.6%, for the quarter ended September 30, 2021 as compared to the same period in 2020. The increase was due primarily to increases in data processing fees of $23,000, compensation and benefits of $20,000, occupancy and equipment expenses of $15,000 and other expenses of $11,000, partially offset by a reduction in the impairment loss on real estate held for sale of $37,000. An impairment of $37,000 was recorded during the three months ended September 30, 2020 whereas no impairment was recorded during the three months ended September 30, 2021.
Noninterest expense increased $426,000, or 9.8%, for the nine months ended September 30, 2021 as compared to the same period in 2020. The increase was due primarily to increases in compensation and benefits of $265,000, occupancy and equipment expenses of $65,000, data processing fees of $40,000, deposit insurance premiums of $27,000, directors’ compensation expense of $19,000 and other expenses of $55,000, partially offset by decreases in professional