Investing in Opportunity Act This bill amends the Internal Revenue Code to authorize the designation of opportunity zones in low-income communities and to provide tax incentives for investments in the zones, including deferring the recognition of capital gains that are reinvested in the zones. Governors may submit nominations for a limited number of opportunity zones to the Department of the Treasury for certification and designation. Governors must give particular consideration to areas that: are currently the focus of mutually reinforcing state, local, or private economic development initiatives to attract investment and foster startup activity; have demonstrated success in geographically targeted development programs such as promise zones, the new markets tax credit, empowerment zones, and renewal communities; and have recently experienced significant layoffs due to business closures or relocations. Treasury must designate zones if a governor fails to submit nominations within a specified period of time. An "opportunity fund" is any investment vehicle organized as a corporation or a partnership to invest in opportunity zones that holds at least 90% of its assets in opportunity zone assets. Taxpayers may temporarily defer the recognition of capital gains that are invested in opportunity zones. Investments in opportunity zones or opportunity funds that are held for at least five years are eligible for capital gains tax reductions or exemptions, depending on how long the investment is held. Treasury must report to Congress on the opportunity zone incentives enacted in this bill, including an assessment of opportunity fund investments at the national and state levels.