Each interim period is considered an integral part of the annual period and, accordingly, we measure our income tax expense using an estimated annual effective tax rate.  A company is required, at the end of each interim reporting period, to make its best estimate of the annual effective tax rate for the full fiscal year and use that rate to provide for income taxes on a current year-to-date basis, as adjusted for discrete taxable events that occur during the interim period.

We recorded an income tax benefit of $0.1 million and $0.2 million in the for the three and nine months ended October 31, 2019, respectively, and we recorded income tax benefits of $0.8 million and $2.4 million for the three and nine months ended October 31, 2018, respectively. Our effective tax rate in fiscal 2020 and in future periods may fluctuate on a quarterly basis as a result of changes in our jurisdictional forecasts where losses cannot be benefitted due to the existence of valuation allowances on our deferred tax assets, changes in actual results versus our estimates, or changes in tax laws, regulations, accounting principles or interpretations thereof.

We review all available evidence to evaluate the recovery of deferred tax assets, including the recent history of losses in all tax jurisdictions, as well as its ability to generate income in future periods. As of October 31, 2019, due to the uncertainty related to the ultimate use of certain deferred income tax assets, we have recorded a valuation allowance on certain deferred assets.

The U.S. Tax Cuts and Job Act (the “2017 Tax Act”) introduced significant changes to U.S. income tax law.  Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system and a one-time tax on the mandatory deemed repatriation of cumulative foreign earnings (the “Transition Tax”) as of December 31, 2017.

We file income tax returns in the U.S. federal jurisdiction, various state jurisdictions and various foreign jurisdictions. We have closed out an audit with the Internal Revenue Service (“IRS”) through fiscal 2013; however, the taxing authorities will still have the ability to review the propriety of certain tax attributes created in closed years if such tax attributes are utilized in an open tax year, such as our federal research and development credit carryovers.

On March 4, 2019, our Board approved and adopted a Tax Benefits Preservation Plan to potentially limit our ability to use net operating loss carryforwards and certain other tax attributes (“NOLs”) to reduce our potential future federal income tax obligations.  In connection with the Tax Benefits Preservation Plan, we declared a dividend of one preferred share purchase right for each share of our common stock issued and outstanding as of March 15, 2019 to our stockholders of record on that date.  The Tax Benefits Preservation Plan expires no later than March 4, 2022, and was approved by our stockholders at our 2019 annual meeting of stockholders on July 11, 2019.