Strategy. Under normal market conditions, and as a fundamental policy, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes) in securities the income from which, in the opinion of counsel to the issuer of each security, is exempt from regular federal individual and, as applicable, the Funds state income tax. The policy stated in the foregoing sentence is a fundamental policy of the Fund and may not be changed without shareholder approval of a majority of the Funds outstanding voting securities, as defined in the Investment Company Act of 1940, as amended (Investment Company Act of 1940 or 1940 Act). In complying with this 80% investment requirement, the Fund may invest in derivatives and other … Show more… Under normal market conditions, and as a fundamental policy, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes) in securities the income from which, in the opinion of counsel to the issuer of each security, is exempt from regular federal individual and, as applicable, the Funds state income tax. The policy stated in the foregoing sentence is a fundamental policy of the Fund and may not be changed without shareholder approval of a majority of the Funds outstanding voting securities, as defined in the Investment Company Act of 1940, as amended (Investment Company Act of 1940 or 1940 Act). In complying with this 80% investment requirement, the Fund may invest in derivatives and other instruments that have economic characteristics similar to the Funds direct investments that are counted toward the 80% investment requirement. The Fund will not invest more than 5% of its net assets in securities that produce income subject to the federal alternative minimum tax (AMT). The Fund invests in municipal securities issued by the governments of states, their political subdivisions (such as cities, towns, counties, agencies and authorities) and the District of Columbia, U.S. territories, commonwealths and possessions or by their agencies, instrumentalities and authorities. These primarily include municipal bonds (long-term (more than one-year) obligations), municipal notes (short-term obligations), interests in municipal leases, and tax-exempt commercial paper. Municipal securities generally are classified as general or revenue obligations. General obligations are secured by the issuers pledge of its full faith, credit and taxing power for the payment of principal and interest. Revenue obligations are bonds whose interest is payable only from the revenues derived from a particular facility or class of facilities, or a specific excise tax or other revenue source. The Fund seeks to maintain a dollar-weighted average effective portfolio maturity of two years or less; however, it can buy securities that have short, intermediate or long maturities. A substantial percentage of the securities the Fund buys may be callable, meaning that the issuer can redeem them before their maturity date. Because of events affecting the bond markets and interest rate changes, the maturity of the portfolio might not meet that target at all times. The foregoing maturity target is not guaranteed and the portfolio managers may deviate from such target in their discretion. The Fund will not invest more than 5% of its total assets in securities that are rated below investment grade (sometimes referred to as junk bonds). The Fund also will not invest more than 15% of its total assets in securities rated below the top three investment grade categories. Each of these restrictions is applied at the time of purchase and the Fund may continue to hold a security whose credit rating has been downgraded or, in the case of an unrated security, after the Funds investment adviser, Invesco Advisers, Inc. (Invesco or the Adviser), has changed its assessment of the securitys credit quality. As a result, credit rating downgrades or other market fluctuations may cause the Funds holdings of these securities to exceed, at times significantly, these restrictions for an extended period of time. Investment grade securities are: (i) securities rated BBB- or higher by S&P Global Ratings (S&P) or Baa3 or higher by Moodys Investors Service, Inc. (Moodys) or an equivalent rating by another nationally recognized statistical rating organization (NRSRO), (ii) securities with comparable short-term NRSRO ratings, or (iii) unrated securities determined by the Adviser to be of comparable quality, each at the time of purchase. Medium- and lower-grade municipal securities are securities rated by S&P or Fitch, Inc. (Fitch) as BBB+ through D (inclusive) for bonds or SP-2 or lower for notes; by Moodys as Baa1 through D (inclusive) for bonds or MIG3 or VMIG3 or lower for notes; or unrated municipal securities determined by the Adviser to be of comparable quality, each at the time of purchase. If two or more NRSROs have assigned different ratings to a security, the Adviser uses the highest rating assigned. The Fund will not invest more than 5% of its total assets in unrated securities. For purposes of the limitations described above regarding unrated securities, such securities do not include securities that are not rated but that the Adviser determines to be comparable to securities of the same issuer that are rated by an NRSRO. The Fund will not invest more than 15% of its total assets in municipal securities issued by the government of a single state, its political sub-divisions, or the District of Columbia, U.S. territory, commonwealth or possession, or their agencies, instrumentalities and authorities. Notwithstanding this limitation, the Fund may invest up to 25% of its total assets in municipal securities issued by each of California, New York, and Texas, or their respective agencies, instrumentalities and authorities. In addition, the Fund will not invest more than 15% of its total assets in a single sector, as determined by the Adviser. This limitation does not apply to investments in the general obligations sector. The Fund can invest in derivative instruments, including futures contracts. The Fund can use futures contracts, including interest rate futures, to reduce exposure to interest rate changes and to manage duration. The Fund may invest up to 20% of its net assets (plus borrowings for investment purposes) in investments that generate income subject to income taxes. Taxable investments include many of the types of securities the Fund would buy for temporary defensive purposes. The Fund does not anticipate investing substantial amounts of its assets in taxable investments under normal market conditions or as part of its normal trading strategies and policies. To the extent the Fund invests in pre-refunded municipal securities collateralized by U.S. government securities, the Fund may treat those securities as investment-grade (AAA) securities even if the issuer itself has a below-investment-grade rating. The Adviser buys and sells securities for the Funds portfolio with a view towards seeking a high level of interest income exempt from federal income tax and selects securities that the Adviser believes entail reasonable credit risk considered in relation to the investment policies of the Fund. As a result, the Fund will not necessarily invest in the highest yielding municipal securities permitted by its investment policies if the Adviser determines that market risks or credit risks associated with such investments would subject the Funds portfolio to undue risk. Show less