to $202.7 million. The increase in average portfolio loans outstanding was concentrated in nonresidential, one to four family owner-occupied residential mortgage loans and multifamily loans. Nonresidential real estate loans increased $6.9 million, one to four family owner-occupied residential mortgage loans increased $4.1 million, and multifamily loans increased $2.5 million and home equity lines of credit increased $615,000 during the quarter ended March 31, 2022. The average yield on loans decreased 43 basis points to 3.82% for the three months ended March 31, 2022 from 4.25% for the three months ended March 31, 2021. The average balance of loans held for sale decreased $7.0 million, or 50.1%, during the quarter ended March 31, 2022 compared to the same quarter in 2021, while the average yield on loans held for sale increased 104 basis points, to 3.04% for the three months ended March 31, 2022 from 2.00% for the same quarter in 2021.
Interest income on securities decreased $6,000, or 30.0%, to $15,000 for the three months ended March 31, 2022 compared to the same period in 2021. The average balance of securities decreased $927,000 to $7.7 million at March 31, 2022. The yield on securities decreased 19 basis points to 0.78% for the three months ended March 31, 2022. The securities portfolio consists entirely of one year adjustable rate and one month floating rate mortgage backed securities. Interest income on other interest-earning assets increased $10,000, or 71.5%, to $23,000 for the three months ended March 31, 2022 compared to the same period in 2021. The yield on other interest-bearing assets increased 70 basis points to 0.93% for the three months ended March 31, 2022. The average balance on other interest-earning assets decreased $12.7 million, or 56.2%, period to period. The balance on Federal Home Loan Bank Stock increased $1.1 million. The dividend rate paid on FHLB stock was 2.00% at March 31, 2022.
Interest Expense. Total interest expense decreased $306,000, or 61.3%, to $194,000 for the quarter ended March 31, 2022 from $500,000 for the quarter ended March 31, 2021. Interest expense on borrowings declined by $206,000 period to period, reflecting the cost-saving effects of management’s strategy to prepay higher cost borrowings in the preceding quarter ended December 31, 2021. Interest expense on deposits decreased $100,000, or 34.2%, to $192,000 for the quarter ended March 31, 2022 compared to the quarter ended March 31, 2021. The decrease in deposit interest expense between the comparable quarters in 2022 from 2021 was primarily due to a 42 basis point decrease in the average cost of deposits, primarily due to the addition of lower rate National CD Rateline funds during the second quarter of 2021.
Interest expense on savings accounts increased $17,000 during the quarter ended March 31, 2022 compared to the quarter ended March 31, 2021, due to an increase of $25.5 million in average savings balances. The increase was primarily attributable to an account established by a local municipality. The average cost of interest-bearing demand deposits remained at 14 basis points for both periods. The average balances in interest-bearing demand accounts increased $1.7 million during the three months ended March 31, 2022 compared to March 31, 2021. Interest expense on certificates of deposit decreased $118,000, or 45.7%. The average cost of certificates decreased 108 basis points to 0.69%. The average balance of certificates of deposit increased $21.1 million to $81.4 million for the three months ended March 31, 2022 compared to the same period ended March 31, 2021.
Interest expense on FHLB advances decreased $206,000, or 99.4%, to $1,000 for the quarter ended March 31, 2022 from the quarter ended March 31, 2021. The average balance of advances decreased $37.2 million, or 96.7%, for the quarter ended March 31, 2022. The average cost of FHLB borrowings decreased 185 basis points to 0.32% for the quarter ended March 31, 2022. The decrease in FHLB Advances was due to the prepayment of advances undertaken in 2021 and replacement of the borrowings with National CD Rateline funds. The entire National CD Rateline portfolio totaled $43.2 million with an average remaining term of 18 months and an average rate of 0.43% as of March 31, 2022.
Net Interest Income. Net interest income increased $420,000, or 29.6%, for the quarter ended March 31, 2022 compared to the same quarter in 2021. The interest rate spread increased to 3.12% for the quarter ended March 31, 2022 compared to 2.33% for the quarter ended March 31, 2021. The net interest margin increased 65 basis points to 3.19% for the quarter ended March 31, 2022.
Provision for Loan Losses. Based on our analysis, we did record a provision for loan losses for the three months ended March 31, 2022 of $21,000. The allowance for loan losses was $1.7 million, or 0.75% of total loans, at March 31, 2022, compared to $1.7 million, or 0.92% of total loans, at March 31, 2021. Given the growth in the loan portfolio in recent months, an increase in the qualitative factor for continued loan growth may be likely and may increase the provision for loan losses. The Company had no net charge-offs during the three-month period ended March 31, 2022. As a percentage of nonperforming loans, the allowance for loan losses was 3,094.7% at March 31, 2022. Total loans past due were $259,000, or 0.1% of total loans, at March 31, 2022.