The increase in interest expense on deposits was due to a 25 basis point increase in the average rate, as well as a $29.4 million increase in the average balance of interest-bearing deposits to $523.1 million for the nine months ended September 30, 2025 from $493.8 million for the nine months ended September 30, 2024. The average rate on interest-bearing deposits was 2.03% for the nine months ended September 30, 2025 compared to 1.78% for the nine months ended September 30, 2024 as rates paid increased and depositors moved money into higher-cost certificates of deposit and money market accounts.
Interest expense on subordinated debentures decreased $590,000, or 29.7%, to $1.4 million for the nine months ended September 30, 2025 compared to $2.0 million for the nine months ended September 30, 2024. The decrease was due to the pay-off in the first quarter of 2024 of $3.0 million in junior subordinated debt assumed in a prior acquisition and the concurrent write-off of the purchase accounting adjustment on that debt.
Net Interest Income. Net interest income was $9.4 million for the three months ended September 30, 2025 compared to $9.3 million for the three months ended September 30, 2024. The net interest margin for the three months ended September 30, 2025 was 4.40% compared to 4.49% for the three months ended September 30, 2024. The increase in net interest income was due to higher average balances of interest earning assets and higher yields on these assets offset by a higher average balance of deposits and higher rates paid on deposits.
Net interest income was $27.1 million for the nine months ended September 30, 2025, compared to $26.2 million in the nine months ended September 30, 2024. The net interest margin for the nine months ended September 30, 2025 was 4.29% compared to 4.25% for the nine months ended September 30, 2024. The increase in net interest income was due to higher average balances of interest earning assets and higher yields on these assets offsetting the increase in interest expense due to a higher volume of deposits and higher rates paid on deposits.
Provision for Credit Losses. We recorded a reversal of the provision for credit losses of $1.0 million for the three months ended September 30, 2025 compared to a reversal of the provision for credit losses of $714,000 for the three months ended September 30, 2024. We recorded a reversal of the provision for credit losses of 539,000 for the nine months ended September 30, 2025 compared to a reversal of the provision for credit losses of $806,000 for the nine months ended September 30, 2024. Our allowance for credit losses was $8.2 million at September 30, 2025 compared to $8.5 million at December 31, 2024. The ratio of our allowance for credit losses to total loans was 1.10% at September 30, 2025 compared to 1.15% at December 31, 2024, while the allowance for credit losses to non-performing loans was 233.5% at September 30, 2025 compared to 212.5% at December 31, 2024.
Non-interest Income. For the three months ended September 30, 2025, noninterest income totaled approximately $684,000 compared to $696,000 for the quarter ended September 30, 2024.
For the nine months ended September 30, 2025 and September 30, 2024, noninterest income totaled $1.9 million.
Non-interest Expense. For the three months ended September 30, 2025, noninterest expense totaled $5.9 million compared to $5.5 million in the three months ended September 30, 2024. Compensation and benefits increased $570,000, primarily due to the costs of the 2024 equity incentive plan. For the quarter ended September 30, 2024, the expenses of the 2024 equity incentive plan were only applicable for one month based on the grant dates of the awards. All other expense categories combined decreased by $165,000 in the quarter ended September 30, 2025 when compared to the quarter ended September 30, 2024.
For the nine months ended September 30, 2025, noninterest expense totaled $17.8 million as compared to $15.3 million in the nine months ended September 30, 2024. Compensation and benefits expense increased $2.9 million. For the nine months ended September 30, 2025, the expenses of the 2024 equity incentive plan were applicable for all nine months compared to one month for the nine month period ended September 30, 2024. The increase in plan expenses totaled $2.9 million in the 2025 year-to-date period when compared to the same period in 2024. All other expense categories combined decreased by $374,000 in the quarter ended September 30, 2025 when compared to the quarter ended September 30, 2024.
Income Tax Expense. For the three months and nine months ended September 30, 2025, income tax expense was $1.4 million for an effective tax rate of 27.9% and $3.1 million for an effective tax rate of 26.4%, respectively. For the three months and nine months ended September 30, 2024, income tax expense was $1.4 million for an effective tax rate of 27.5% and $3.8 million for an effective tax rate of 27.9%, respectively. The lower effective tax rate in the nine-month period ended September 30, 2025 was due to an accrual adjustment made in the first quarter.