based compensation expense of $343,000 and $416,000 for the three months ended December 31, 2020 and 2021, respectively. Research and development expenses increased by 5.5% from $17.2 million in the nine months ended December 31, 2020 to $18.2 million in the nine months ended December 31, 2021. The increase in research and development spending was primarily related to an increase of $1.1 million in payroll related expenses and lesser increases in stock-based compensation expense and facilities related expenses partially offset by lesser decreases outside consulting expenses and other fees and patent related legal fees. Research and development expenses included stock-based compensation expense of $1.1 million and $1.3 million for the nine months ended December 31, 2020 and 2021, respectively.
Selling, General and Administrative Expenses. Selling, general and administrative expenses increased by 8.8% from $2.6 million in the three months ended December 31, 2020 to $2.8 million in the three months ended December 31, 2021. An increase of $143,000 in payroll related expenses and a lesser increase in independent sales representatives commissions was partially offset by decreases professional fees and outside consulting expenses. Selling, general and administrative expenses included stock-based compensation expense of $262,000 and $266,000 for the three months ended December 31, 2020 and 2021, respectively. Selling, general and administrative expenses increased by 6.5% from $8.1 million in the nine months ended December 31, 2020 to $8.7 million in the nine months ended December 31, 2021. An increase of $175,000 in independent sales representatives commissions and lesser increases in payroll related expenses, professional fees, general insurance expense and stock-based compensation expense was partially offset by a decrease in travel related expenses and dues and subscription related expenses. Selling, general and administrative expenses included stock-based compensation expense of $732,000 and $783,000 for the nine months ended December 31, 2020 and 2021, respectively.
Interest Income and Other Expense, Net. Interest and other expense, net decreased by $10,000 from income of $25,000 in the three months ended December 31, 2020 to income of $15,000 in the three months ended December 31, 2021. Interest income decreased by $30,000 primarily due to lower interest rates received on our cash and short-term and long-term investments and a lesser amount of investments. Foreign exchange losses were $25,000 for the three months ended December 31, 2020 compared to $5,000 for the three months ended December 31, 2021. Interest and other expense, net decreased by $128,000 from income of $115,000 in the nine months ended December 31, 2020 to an expense of $13,000 in the nine months ended December 31, 2021. Interest income decreased by $184,000 primarily due to lower interest rates received on our cash and short-term and long-term investments and a lesser amount of investments. Foreign exchange losses were $129,000 for the nine months ended December 31, 2020 compared to $73,000 for the nine months ended December 31, 2021. The exchange losses in each period were related to our Taiwan branch operations and our operations in Israel.
Provision (benefit) for Income Taxes. The provision (benefit) for income taxes decreased from a provision of $90,000 in the three months ended December 31, 2020 to $64,000 in the three months December 31, 2021 and decreased from a provision of $639,000 in the nine months ended December 31, 2020 to a benefit of ($66,000) in the nine months December 31, 2021. The provision for income taxes for the nine months ended December 31, 2020 included a settlement of an income tax audit in Israel for fiscal years 2016 through fiscal 2019 which resulted in a discrete tax provision of $479,000. The benefit from income taxes for the nine months ended December 31, 2021 included a benefit of ($220,000) related to the approval by the Israel tax authorities of a “Preferred Company” tax rate that was retroactively applied to fiscal 2018 and subsequent fiscal years.
Net Loss. Net loss was $5.2 million in the three months ended December 31, 2020 compared to $4.6 million in the three months ended December 31, 2021 and was $16.5 million in the nine months ended December 31, 2020 compared to $13.4 million in the nine months ended December 31, 2021. These fluctuations were primarily due to the changes in net revenues, gross profit and operating expenses discussed above.
Liquidity and Capital Resources
As of December 31, 2021, our principal sources of liquidity were cash, cash equivalents and short-term investments of $48.1 million compared to $54.0 million as of March 31, 2021.
Net cash used in operating activities was $9.9 million for the nine months ended December 31, 2021 compared to $11.4 million for the nine months ended December 31, 2020. The primary uses of cash in the nine months ended December 31, 2021 was the net loss of $13.4 million and increases in prepaid expenses and other