ILLUMINA INC

Our effective tax rate may vary from the U.S. federal statutory tax rate due to the change in the mix of earnings in tax jurisdictions with different statutory rates, benefits related to tax credits, and the tax impact of non-deductible expenses and other permanent differences between income before income taxes and taxable income.

Our effective tax rate for Q1 2024 was (15.3)% compared to 103.9% in Q1 2023. The variance from the U.S. federal statutory tax rate of 21% in Q1 2024 was primarily attributable to the $21 million income tax expense impact of research and development expense capitalization for tax purposes, and the $18 million income tax expense impact of GRAIL pre-acquisition net operating losses on global intangible low-taxed income (GILTI), the utilization of U.S.

foreign tax credits, and the Pillar Two global minimum top-up tax. This was partially offset by the mix of earnings in jurisdictions with lower statutory tax rates than the U.S. federal statutory tax rate, such as in Singapore.

Other than in Q2 2023, we historically calculated the provision/(benefit) for income taxes for interim periods utilizing an estimated annual effective tax rate applied to the income/(loss) for the reporting period. In accordance with the authoritative guidance for accounting for income taxes in interim periods, we concluded for Q1 2024 that it was appropriate to determine the provision for income taxes utilizing the year-to-date effective tax rate method. Since minor changes in the estimated income/(loss) before income taxes would result in significant changes in the estimated annual effective tax rate, we determined the year-to-date effective tax rate method would provide a more reliable estimate of the provision for income taxes for Q1 2024.

As of March 31, 2024 and December 31, 2023, prepaid income taxes, included within prepaid expenses and other current assets on the condensed consolidated balance sheets, were $64 million and $75 million, respectively.