December 31, 2020 from $6.5 million for the year ended December 21, 2019, while the average yield on investment securities decreased 90 basis points to 1.50% for 2020 from 2.40% for 2019. The average balance of other interest-earning assets increased $9.5 million, or 111.3%, to $18.0 million for the year ended December 31, 2020 from $8.5 million for the year ended December 31, 2019, and the average yield on other interest-earning assets decreased 143 basis points to 0.45% for 2020 from 1.88% for 2019.
Interest Expense. Total interest expense decreased $347,000, or 17.9%, to $1.6 million for the year ended December 31, 2020 from $1.9 million for the year ended December 31, 2019. The decrease was primarily due to a decrease of $250,000, or 19.8%, in interest expense on deposits and a decrease of $97,000, or 14.2%, in interest expense on FHLB advances. The average balance of interest-bearing deposits decreased $3.5 million, or 5.9%, to $55.9 million for the year ended December 31, 2020 from $59.4 million for the year ended December 31, 2019, and the average cost of interest-bearing deposits decreased 31 basis points to 1.81% for 2020 from 2.12% for 2019. The average balance of FHLB advances decreased $1.5 million, or 6.2%, to $22.3 million for the year ended December 31, 2020 from $23.8 million for the year ended December 31, 2019. The average cost of these advances decreased 25 basis points to 2.62% for 2020 from 2.87% for 2019.
Net Interest Income. Net interest income decreased $466,000, or 25.1%, to $1.4 million for the year ended December 31, 2020 from $1.9 million for the year ended December 31, 2019. Average net interest-earning assets increased $5.3 million year to year. This increase was due primarily to an increase in the average balance of other interest-bearing assets year to year. Our interest rate spread decreased 56 basis points to 1.06% for the year ended December 31, 2020 from 1.62% for the year ended December 31, 2019, and our net interest margin decreased 49 basis points to 1.45% for the year ended December 31, 2020 from 1.94% for the year ended December 31, 2019. The decreases in interest rate spread and net interest margin were primarily the result of a decreasing interest rate environment during 2020 causing a mortgage loan refinance boom resulting in our interest-earning assets repricing at a faster rate than the costs on our interest-bearing liabilities.
Provision for Loan Losses. We recorded credits in the provision for loan losses of $2,000 for the year ended December 31, 2020 and $9,000 for the year ended December 31, 2019. The decrease in the credit in the provision for loan losses in 2020 compared to 2019 resulted from our analysis of the factors described in “Critical Accounting Policies – Allowance for Loan Losses.” The allowance for loan losses was $850,000, or 1.22% of total loans, at December 31, 2020, compared to $850,000, or 1.08% of total loans, at December 31, 2019. Classified (substandard, doubtful and loss) loans decreased to $559,000 at December 31, 2020 from $567,000 at December 31, 2019. There were no non-performing loans at December 31, 2020 or December 31, 2019. Net recoveries were $2,000 in 2020 compared to $9,000 in 2019, a decrease of $7,000.
Noninterest Income. Noninterest income increased $234,000, or 31.6%, to $975,000 for the year ended December 31, 2020 from $741,000 for the year ended December 31, 2019. The increase was primarily due to an increase in fees on loans sold of $258,000. This increase was partially offset by a decreases in service charges and other income of $16,000, gains on sales of securities of $6,000 and income from life insurance of $2,000.
Noninterest Expense. Noninterest expense increased $119,000, or 4.9%, to $2.5 million for 2020 from $2.4 million for 2019. The increase was due primarily to an increase of $50,000, or 3.3%, in salaries and employee benefits, primarily from increased commissions paid on higher loan volume in 2020. The increase in noninterest expense also resulted from increases of $47,000 or 235.0% in legal fees, $39,000, or 24.7%, in accounting and consulting expense, $12,000 or 22.2% in FDIC deposit insurance premiums and $21,000, or 9.5% in other expenses. The increase in accounting and consulting expense and legal fees resulted from