MFS California Municipal Fund is a closed-end fund. The fund's investment objective is to seek high current income exempt from federal income tax and California personal income tax as well as capital appreciation. It offers a dividend reinvestment and cash purchase plan that allows common shareholders to reinvest either all the distributions paid by the fund or only the long-term capital gains. The fund invests majority of its net assets, including assets attributable to preferred shares and borrowings for investment purposes, in debt securities the interest on which in the opinion of issuer counsel is exempt from federal regular income tax and California personal income tax. It invests the fund's assets in municipal instruments.