2020 period. The increase is driven by costs associated with various system modernization in our claims, billing and underwriting areas and an increase in contingent commission expenses.
Interest Expense. Interest expense was $129 for the three months ended March 31, 2021 compared to $47 for the comparable 2020 period. The credit facility commitment fee included in interest expense was $19 for the three months ended March 31, 2021 and 2020.
Income Tax Expense (Benefit). Our effective tax rate was 20.1% and 29.7% for the quarters ended March 31, 2021 and 2020, respectively. The effective tax rate for the quarter ended March 31, 2021 was lower than the statutory rate primarily due to the effects of tax-exempt investment income and the impact of stock-based compensation. The effective tax rate for the quarter ended March 31, 2020 is higher than the statutory rate due to the impact of the change in unrealized gains on equity securities.
Net Income (Loss). Net income for the three months ended March 31, 2021 was $36,174 compared to a net loss of $1,990 for the comparable 2020 period. The three months ended March 31, 2020 was affected by the market volatility associated with the onset of the COVID-19 pandemic which caused a significant decrease in the change in unrealized gains on equity investments.
Non-GAAP Operating Income. Non-GAAP operating income as defined above was $28,856 for the three months ended March 31, 2021 compared to $24,182 for the comparable 2020 period. The increase in Non-GAAP operating income was primarily the result of a decrease in loss and loss adjustment expenses compared to the prior period.
Liquidity and Capital Resources
As a holding company, Safety’s assets consist primarily of the stock of our direct and indirect subsidiaries. Our principal source of funds to meet our obligations and pay dividends to shareholders, therefore, is dividends and other permitted payments from our subsidiaries, principally Safety Insurance. Safety is the borrower under our credit facility.
Safety Insurance’s sources of funds primarily include premiums received, investment income, and proceeds from sales and redemptions of investments. Safety Insurance’s principal uses of cash are the payment of claims, operating expenses and taxes, the purchase of investments, and the payment of dividends to Safety.
Net cash provided by operating activities was $12,523 during the three months ended March 31, 2021 compared to net cash used for operating activities of $28,515 during the three months ended March 31, 2020. Our operations typically generate positive cash flows from operations as most premiums are received in advance of the time when claim and benefit payments are required. Net cash used for operating activities during the three months ended March 31, 2020 was the result of the timing of expense payments and changes in other liabilities which is driven by the reclassification of cash to offset outstanding claims checks. Positive operating cash flows are expected in the future to meet our liquidity requirements.
Net cash used for investing activities was $814 during the three months ended March 31, 2021 compared to net cash provided by investing activities of $20,296 during the three months ended March 31, 2020. Fixed maturities, equity securities, and other invested assets purchased were $80,439 for the three months ended March 31, 2021 compared to $47,813 for the comparable prior year period. Proceeds from maturities, redemptions, calls and sales, of securities were $82,498 during the three months ended March 31, 2021 compared to $71,086 for the comparable prior year period.
Net cash used for financing activities was $13,915 during the three months ended March 31, 2021 compared to net cash provided by financing activities of $5,379 during the three months ended March 31, 2020. The net cash used for financing activities during the three months ended March 31, 2021 consisted of dividend payments to shareholders. The net cash provided by financing activities during the three months ended March 31, 2020 was primarily driven by proceeds from the FHLB-Boston loan. On March 17, 2020, the Company borrowed $30,000 from the FHLB-Boston for a term of five years, bearing interest at a rate of 1.42%. Interest is payable monthly and the principal is due on the