Quarterly Trends and Seasonality
Our overall operating results fluctuate from quarter to quarter as a result of a variety of factors, some of which are outside of our control. Our historical results should not be considered a reliable indicator of our future results of operations.
We experience fluctuations in revenues and related costs on a seasonal basis, which are primarily seen in our fiscal third quarter, which ends on March 31 of each year. Specifically, our recurring revenue is positively impacted in our fiscal third quarter as a result of our preparation of W-2 documents for our clients’ employees in advance of tax filing requirements. The seasonal fluctuations in revenues also positively impact gross profits during our fiscal third quarter. Our historical results for our fiscal third quarter should not be considered a reliable indicator of our future results of operations. Our interest income earned on funds held for clients is also positively impacted during our fiscal third quarter as a result of our increased collection of funds held for clients. Certain payroll taxes are primarily collected during our fiscal third quarter and subsequently remitted.
Critical Accounting Policies and Estimates
Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with GAAP. The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenue and expenses. In accordance with GAAP, we base our estimates on historical experience and on various other assumptions that we believe are reasonable under the circumstances. Actual results may differ from our estimates under different assumptions or conditions and, to the extent that there are differences between our estimates and actual results, our future financial statement presentation, financial condition, results of operations and cash flows will be affected.
In March 2020, the World Health Organization declared the outbreak of COVID-19 as a pandemic which has caused a global slowdown of economic activity. The duration and severity of the COVID-19 pandemic, and the effect the pandemic will have on our clients and general economic conditions, remains uncertain and difficult to predict. Accounting estimates used in the preparation of these consolidated financial statements may change as new events occur, more experience and additional information is acquired, and the operating environment evolves including the ongoing impact of COVID-19. Refer to “Part I. Item 1A. Risk Factors” in our Annual Report on Form 10-K filed with the SEC on August 7, 2020 for risks related to the COVID-19 pandemic on its business and financial performance.
Our critical accounting policies and use of estimates are disclosed in our audited consolidated financial statements for the year ended June 30, 2020 included in our Annual Report on Form 10-K.
Liquidity and Capital Resources
Our primary liquidity needs are related to the funding of general business requirements, including working capital requirements, research and development, and capital expenditures. As of March 31, 2021, our principal sources of liquidity were $175.5 million of cash and cash equivalents and $6.8 million of total corporate investments. In July 2019, we entered into and currently maintain a five-year revolving credit agreement. This credit agreement provides for a $250.0 million senior revolving credit facility which may be increased up to $375.0 million. In fiscal 2020, we borrowed $100.0 million under this credit facility, which we repaid in the third quarter of fiscal 2021. Refer to Note 8 of the Notes to the Unaudited Consolidated Financial Statements for additional detail on the credit agreement.
We invest portions of our excess cash and cash equivalents in highly liquid, investment-grade marketable securities. These investments consist of commercial paper, asset-backed debt securities, corporate debt issuances and U.S. Treasury securities with credit quality ratings of A-1 or higher. As of March 31, 2021, we had not recognized any credit impairment losses related to our investment portfolio.
In order to grow our business, we intend to increase our personnel and related expenses and to make significant investments in our platform, data centers and general infrastructure. The timing and amount of these investments will vary based on our financial condition, the rate at which we add new clients and new personnel and the scale of our