Nuveen California Select Tax-Free Income Portfolio Announces Monthly Distribution, Payable on June 3, 2019

Nuveen California Select Tax-Free Income Portfolio (the Fund) is a diversified closed-end management investment company. The Fund's investment objectives are to provide current income exempt from regular federal and California income tax and to enhance portfolio value relative to the municipal bond market by investing in tax-exempt municipal bonds that the Fund's investment adviser believes are underrated or undervalued or that represent municipal market sectors that are undervalued. The Fund invests 80% of its assets in municipal securities and other related investments that pay interest exempt from federal and California income taxes. The Fund invests up to 20% of its managed assets in municipal securities that are subject to the federal alternative minimum tax (AMT Bonds). It invests up to 15% of its managed assets in inverse floating rate securities. The Fund's investment advisor is Nuveen Fund Advisors, LLC.