Comparison of Operating Results for the Three Months Ended March 31, 2021 and 2020
General. Net income increased by $540,000, or 12.1%, from $4.5 million for the three months ended March 31, 2020 to $5.0 million for the three months ended March 31, 2021. The increase in net income was due to a $1.1 million decrease in loan loss provisions and a $938,000 increase in non-interest income. These increases to net income were partially offset by a $1.3 million decrease in net interest income and a $201,000 increase in income tax expense.
Net Interest Income. Net interest income decreased by $1.3 million, or 9.0%, to $13.2 million for the three months ended March 31, 2021 from $14.5 million for the three months ended March 31, 2020. Interest income decreased by $3.5 million, or 18.7%, due to a 69 basis point decrease in the average yield of interest-earning assets, which was partially offset by a $775,000 increase in the average balance of interest-earning assets. Interest expense decreased by $2.2 million, or 53.3%, due to a 49 basis point decrease in the cost of average interest-bearing liabilities, which was augmented by a $14.8 million decrease in the average balance of interest-bearing liabilities. The interest rate spread and net interest margin were 2.54% and 2.61% respectively, for the three months ended March 31, 2021, compared to 2.74% and 2.87%, respectively, for the three months ended March 31, 2020. The decreases in the interest rate spread and in the net interest margin are attributable to the 69 basis point decrease in the yield on average interest-bearing assets that was partially offset by the 49 basis point decrease in the cost of average interest-earning liabilities.
Interest Income. Interest income decreased by $3.5 million, or 18.7%, to $15.1 million for the three months ended March 31, 2021 from $18.6 million for the three months ended March 31, 2020. Interest income on loans decreased by $2.4 million, or 15.6%, to $13.0 million for the three months ended March 31, 2021 from $15.5 million for the three months ended March 31, 2020. The decrease in interest income on loans occurred because the average balance of loans decreased by $197.3 million, or 12.5%, and the average loan yield decreased by 14 basis points. The decrease in the average balance occurred as loan repayments and loan sales exceeded new loan originations. Interest income on securities decreased by $955,000, or 34.4%, to $1.8 million for the three months ended March 31, 2021 from $2.8 million for the three months ended March 31, 2020. The decrease in interest income on securities occurred primarily because the average balance of securities decreased by $91.2 million, or 24.9%, as security repayments and sales exceeded security purchases. The decrease in interest income on securities was augmented by a 38 basis point decrease in the average yield on securities, which occurred as higher yielding securities were paid off or sold and replaced with purchases of lower yielding securities in the current low interest rate environment.
Interest Expense. Interest expense decreased by $2.2 million, or 53.3%, to $1.9 million for the three months ended March 31, 2021 from $4.1 million for the three months ended March 31, 2020. Interest expense on interest-bearing deposits decreased by $1.8 million, or 57.8%, from $3.1 million for the three months ended March 31, 2020 to $1.3 million for the three months ended March 31, 2021. The decrease in interest expense on interest-bearing deposits was primarily due to a 46 basis point decrease in the average rate paid on interest-bearing deposits. The decrease in the average rate paid on interest bearing deposits was primarily due to lower interest rates offered on certificates of deposit and savings accounts. During the three months ended March 31, 2021, the average rate paid on certificates of deposit decreased by 53 basis points as average rates dropped from 1.79% to 1.26% as higher rate certificates of deposit matured. The average rate paid on savings accounts decreased by 29 basis points as average rates dropped from 0.43% to 0.14%. The decrease in the average rates on certificates of deposit and savings accounts occurred because of a decline in market interest rates. Interest expense on Federal Home Loan Bank (FHLB) advances decreased by $359,000, or 40.1%, from $895,000 for the three months ended March 31, 2020 to $536,000 for the three months ended March 31, 2021. The decrease in interest expense on FHLB advances was primarily due to a 77 basis point decrease in the average rate paid and a $15.0 million decrease in the average balance on FHLB advances. The decrease in the average rate paid on FHLB advances was due to restructuring of $82.0 million of FHLB advances in the year ended December 31, 2020. This transaction lowered the average cost of FHLB advances from 2.28% to 1.52% and extended the average maturity date by 1.9 years. The restructuring was accounted for as a continuation of the existing borrowings with any prepayment fees recognized as an adjustment to the future cost of the restructured advances. We primarily funded our operations with additional deposits, borrowings, proceeds from loan and security sales and principal repayments on loans and mortgage-backed securities.
Provision for Loan Losses. We recorded a reversal of provisions for loan losses of $913,000 for the three months ended March 31, 2021 and recorded provisions of $217,000 for the three months ended March 31, 2020. The