ended December 31, 2022, respectively, compared to 2.50% for the three and six months ended December 31, 2021, respectively. Additionally, average net interest-earning assets increased by $70.7 million and $79.9 million to $755.3 million and $750.6 million for the three and six months ended December 31, 2022, respectively, compared to $684.6 million and $670.7 million for the three and six months ended December 31, 2021, respectively.
Interest income increased $7.1 million, or 65.7%, to $18.0 million for the three months ended December 31, 2022, from $10.9 million for the three months ended December 31, 2021. Interest income increased $11.7 million, or 54.5%, to $33.2 million for the six months ended December 31, 2022, from $21.5 million for the six months ended December 31, 2021. Increases in interest income for the three and six months ended December 31, 2022 were driven by a significant increase in variable rate loan yields and yields on interest-earning deposits with banks due to rising market interest rates, as well as due to market related increases in interest rates on new loans and securities.
Interest expense increased $484,000, or 134.4%, to $844,000 for the three months ended December 31, 2022 from $360,000 for the three months ended December 31, 2021. Interest expense increased $621,000, or 83.8%, to $1.4 million for the six months ended December 31, 2022 from $741,000 for the six months ended December 31, 2021. The average cost of interest-bearing liabilities increased by 18 and 12 basis points to 0.32% and 0.26% for the three and six months ended December 31, 2022, respectively, compared to 0.14% for the three and six months ended December 31, 2021, respectively. The average cost of interest-bearing liabilities increased for the three and six months ended December 31, 2022, as the Federal Reserve Board raised the Federal Funds target rate throughout calendar year 2022. We continue to monitor the effects the increases in market rates are having on deposit rates and we anticipate the impact will lead to an increase in rates on interest-bearing liabilities.
Net interest margin increased 144 and 111 basis points to 3.85% and 3.52% for the three and six months ended December 31, 2022, respectively, compared to 2.41% for the three and six months ended December 31, 2021, respectively.
Asset Quality and Loan Loss Provision
We recorded a benefit to the provision for loan losses of $400,000 and $280,000 for the three and six months ended December 31, 2022, respectively, compared to no provision and $250,000 in provision recorded for the three and six months ended December 31, 2021, respectively. The benefit recorded to the provision for the three and six months ended December 31, 2022 was primarily due to improved credit quality and lower net charge-offs.
We recorded net recoveries of $22,000 for the three months ended December 31, 2022, compared to net charge-offs of $433,000 for the three months ended December 31, 2021 and net charge-offs of $52,000 for the six months ended December 31, 2022, compared to net charge-offs of $871,000 for the six months ended December 31, 2021.
Non-performing assets increased to $18.5 million, or 1.01% of total assets, at December 31, 2022, compared to $15.1 million, or 0.82% of total assets, at December 31, 2021. The allowance for loan losses was $22.2 million, or 2.07% of total loans outstanding, at December 31, 2022 and $22.6 million, or 2.23% of total net loans outstanding, at December 31, 2021.
Noninterest Income and Noninterest Expense
Noninterest income was consistent at $3.9 million for the three months ended December 31, 2022 and for the three months ended December 31, 2021. Noninterest income increased $603,000, or 8.4%, to $7.8 million for the six months ended December 31, 2022 as compared to $7.1 million for the six months ended December 31, 2021. The increase for the six months ended December 31, 2022 compared to the six months ended December 31, 2021 was primarily due to an increase in bank-owned life insurance income of $411,000 and an increase in insurance and wealth management services revenue of $359,000, offset in part by a decrease in bank fees and service charges of $221,000. The increase in bank-owned life insurance income was due to a gain recognized from a death benefit. The increase in insurance and wealth management services revenue was primarily due to the recent wealth management acquisitions. The decrease in bank fees and service charges was primarily due to lower deposit service charges.