The provision for loan losses increased by $1.5 million, from a credit of $954,000 for the quarter ended September 30, 2021 to an expense of $545,000 for the current quarter. The provision for loan losses increased by $3.3 million, from a credit of $2.2 million for the nine months ended September 30, 2021 to an expense of $1.1 million for the nine months ended September 30, 2022. In 2021, the credit to the provision for the three and nine months ended September 30, 2021 was primarily attributable to a decline in loan balances, exclusive of PPP loans, a reduction in specific allocations to the allowance for loan losses and a general improvement in economic conditions as our customers showed signs of recovering from the pandemic. An increase in indirect automobile loan balances in 2022 was the primary factor leading to the increase in the provision.
Net charge-offs increased $84,000 to $222,000 for the quarter ended September 30, 2022 from $138,000 for the comparable quarter in 2021 primarily due to increased charge-offs in our indirect automobile portfolio as loan balances increased. Net charge-offs for the nine months ended September 30, 2022 totaled $179,000 compared to net charge-offs of $428,000 for the comparable period in 2021. The year-to-date decrease in 2022 was primarily due to a $143,000 recovery of a residential mortgage loan, pricing gains on the sales of repossessed vehicles as used car prices have risen significantly, and an improvement in the overall economic environment. There was a general overall improvement in loan quality during the first nine months of 2022 as the percentage of overdue account balances to total loans decreased to 1.45% as of September 30, 2022 from 1.58% as of December 31, 2021 and non-performing assets decreased $2.0 million.
Non-interest income totaled $1.4 million for the three months ended September 30, 2022, a decrease of $250,000, or 15.3%, from the comparable period in the prior year, due primarily to a decrease in the net gain on sales of mortgage loans as activity decreased due to fewer originations in the increasing interest rate environment and as some higher-rate loans were added to the portfolio. Gain on sales of mortgage loans decreased $355,000, or 70.7%, compared to the prior year quarter as the Company sold $5.1 million of residential mortgage loans in the third quarter of 2022 as compared to $16.3 million in the third quarter of 2021. The net decrease was partially offset by an increase in service charges on deposit accounts of $49,000, or 7.4%, as transaction volume increased and an increase in other non-interest income of $67,000.
For the nine months ended September 30, 2022, total non-interest income decreased $1.1 million, or 19.8%, from the comparable period in the prior year. The reduction between periods was mostly due to the decrease in the gain on the sale of mortgage loans of $1.3 million, or 61.5%, the 2021 one-time gain from the collection of a life insurance claim of $195,000 and a net realized loss in 2022 from the sale of securities of $170,000, partially offset by an increase in service charges on deposit accounts of $234,000, an improvement in investment advisory income of $120,000, a $69,000 increase in the cash value of life insurance, and a net improvement of $167,000 in other income items.
For the third quarter of 2022, non-interest expense totaled $9.2 million, an increase of $101,000, or 1.1%, over the comparable 2021 period. The increase was primarily due to an increase in salaries and benefits of $195,000, or 3.8%, due to new hires, annual merit increases, production incentives and employee benefit increases, as well as the competitive pressures of the current job market. For the three months ended September 30, 2022, occupancy expenses increased $37,000, or 3.5%, primarily resulting from inflationary pressures on our service contracts. Data processing costs increased $29,000, FDIC insurance costs increased $25,000 and marketing expense increased by $21,000. These increases were partially offset by decreased professional fees of $20,000 and a decrease in other non-interest expenses of $179,000, or 10.7%.
For the nine months ended September 30, 2022, non-interest expense totaled $27.8 million, an increase of $1.9 million, or 7.2%, over the comparable 2021 period. The increase was primarily due to an increase in salaries and benefits of $1.6 million, or 11.1%, due to branch expansion, new hires, annual merit increases, production incentives and employee benefit increases, as well as the competitive pressures of the current job market. For the nine months ended September 30, 2022, occupancy expenses increased $342,000, or 11.2%, as a result of the additional rent, depreciation and other expenses related to branch expansion. The addition of branches was also primarily responsible for increased data processing costs of $152,000, increased marketing expense of $105,000 and increased FDIC insurance costs of $60,000. These increases were partially offset by decreased professional fees of $83,000 and a decrease in other non-interest expenses of $357,000, or 7.8%. The decrease in other non-interest expense was