offset by a decrease in time deposits. As a result of the changes in interest-earning assets and interest-bearing liabilities, the net interest rate spread and net interest rate spread on a tax-equivalent basis(1) was 2.82% and 2.99%, respectively, for the nine months ended September 30, 2022 from 2.81% and 2.99%, respectively, for the nine months ended September 30, 2021. The net interest margin and 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.
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.
Noninterest income increased $44,000, or 4.9%, for the nine months ended September 30, 2022 as compared to the same period in 2021, due primarily to increases of $64,000 and $20,000 in deposit account service charges and ATM and debit card fee income, respectively, and a $36,000 gain on life insurance, partially offset by a reduction in brokered loans fees of $73,000.
Noninterest expense increased $116,000, or 7.5%, for the quarter ended September 30, 2022 as compared to the same period in 2021. The increase was due primarily to increases in compensation and benefits of $34,000, occupancy and equipment expenses of $22,000, data processing expenses of $15,000, directors’ compensation of $14,000 and other expenses of $18,000.
Noninterest expense increased $173,000, or 3.6%, for the nine months ended September 30, 2022 as compared to the same period in 2021. The increase was due primarily to increases in occupancy and equipment expenses of $32,000, data processing expenses of $31,000, professional fees of $24,000, a loss on the disposal of premises and equipment of $17,000, directors’ compensation expenses of $12,000 and other expenses of $45,000, which is mostly attributable to increased advertising expenses.
The Company recorded an income tax expense of $31,000 for the quarter ended September 30, 2022, compared to an income tax expense of $33,000 for the same period in 2021. Income tax expense for the nine months ended September 30, 2022 was $89,000 compared to an expense of $56,000 for the same period in 2021 resulting from an increase in our effective tax rate to 5.6% for 2022 compared to 4.4% for 2021. The increase in the effective tax rate is primarily due to an increase in pre-tax income generated from core banking activities.
Balance Sheet Review
Total assets as of September 30, 2022 were $264.5 million compared to $254.3 million at December 31, 2021. The increase in total assets was primarily due to increases in net loans of $19.9 million, other assets of $5.1 million and Federal Home Loan Bank stock of $1.0 million, partially offset by decreases in cash and cash equivalents of $12.4 million and investment securities of $3.6 million. The increase in net loans was due primarily to increases of $11.2 million in commercial real estate loans, $3.7 million in commercial business loans, $2.4 million in commercial real estate construction loans and $2.0 million in multi-family residential loans. The increase in other assets was due primarily to a $5.1 million increase in net deferred tax assets, largely attributable to the tax effect on the unrealized loss on available for sale securities. Investment securities decreased due primarily to a $20.0 million unrealized loss on available for sale securities and $9.2 million in scheduled principal payments, calls and maturities of mortgage-backed and tax-exempt securities, partially offset by $26.0 million in purchases of available for sale investment securities. Total liabilities, comprised mostly of deposits, increased $26.0 million to $233.7 million as of September 30, 2022. The increase was due primarily to a $21.0 million increase in FHLB borrowings and a $6.0 million increase in interest-bearing deposits, partially offset by a $1.0 million decrease in noninterest-bearing deposits.
Credit Quality
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 non-performing loans were current on their