our ability to anticipate future market needs and opportunities; and any unanticipated accounting charges. The forward-looking statements contained in this press release are also subject to other risks and uncertainties, including those more fully described in our filings with the Securities and Exchange Commission, including our Annual Report on Form 10-K and Quarterly Reports on Form 10-Q.
The forward-looking statements in this press release are based on information available to Qualys as of the date hereof, and Qualys disclaims any obligation to update any forward-looking statements, except as required by law.
Non-GAAP Financial Measures
In addition to reporting financial results in accordance with GAAP, Qualys provides investors with certain non-GAAP financial measures, including non-GAAP gross profit, non-GAAP gross margin, non-GAAP operating expenses, non-GAAP operating income, non-GAAP net income, non-GAAP net income per diluted share, Adjusted EBITDA (defined as earnings before interest expense, interest income and other income (expense), net, income taxes, depreciation, amortization, and stock-based compensation) and non-GAAP free cash flows (defined as cash provided by operating activities less purchases of property and equipment (net of proceeds from disposal) and principal payments under finance lease obligations).
In computing non-GAAP financial measures, Qualys excludes the effects of stock-based compensation expense, amortization of intangible assets from acquisitions, non-recurring items and for non-GAAP net income, certain tax effects. Qualys believes that these non-GAAP financial measures help illustrate underlying trends in its business that could otherwise be masked by the effect of the income or expenses that are excluded in non-GAAP gross profit, non-GAAP gross margin, non-GAAP operating expenses, non-GAAP operating income, non-GAAP net income, non-GAAP net income per diluted share, Adjusted EBITDA and non-GAAP free cash flows.
Furthermore, Qualys uses some of these non-GAAP financial measures to establish budgets and operational goals for managing its business and evaluating its performance. Qualys believes that non-GAAP gross profit, non-GAAP gross margin, non-GAAP operating expenses, non-GAAP operating income, non-GAAP net income, non-GAAP net income per diluted share, Adjusted EBITDA and non-GAAP free cash flows provide additional tools for investors to use in comparing its recurring core business operating results over multiple periods with other companies in its industry.
Although Qualys does not focus on or use quarterly billings in managing or monitoring the performance of its business, Qualys provides calculated current billings (defined as total revenues recognized in a period plus the sequential change in current deferred revenue in the corresponding period) for the convenience of investors and analysts in building their own financial models.
In order to provide a more complete picture of recurring core operating business results, the Company’s non-GAAP net income and non-GAAP net income per diluted share include adjustments for non-recurring income tax items and certain tax effects of non-GAAP adjustments to achieve the effective income tax rate on a non-GAAP basis. The Company’s non-GAAP effective tax rate may differ from the GAAP effective income tax rate as a result of these income tax adjustments. The Company believes its estimated non-GAAP effective income tax rate of 24% in 2023 is a reasonable estimate under its current global operating structure and core business operations. The Company may adjust this rate during the year to take into account events or trends that it believes materially impact the estimated annual rate. The non-GAAP effective income tax rate could be subject to change for a number of reasons, including but not limited to, significant changes resulting from tax legislation, material changes in geographic mix of revenues and expenses and other significant events.
The presentation of this non-GAAP financial information is not intended to be considered in isolation or as a substitute for results prepared in accordance with GAAP. A reconciliation of the non-GAAP financial measures discussed in this press release to the most directly comparable GAAP financial measures is included with the financial statements contained in this press release. Management uses both GAAP and non-GAAP information in evaluating and operating its business internally and as such has determined that it is important to provide this information to investors.
