Label

Element

Value

Prospectus [Line Items]

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Document Type

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497

Document Period End Date

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May 31, 2021

Entity Registrant Name

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JOHN HANCOCK MUNICIPAL SECURITIES TRUST

Entity Central Index Key

dei_EntityCentralIndexKey

0000857769

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

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false

Document Creation Date

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Dec. 09, 2021

Document Effective Date

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Dec. 09, 2021

(John Hancock Tax-Free Bond Fund - Classes A, C, I and R6)

Prospectus [Line Items]

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Strategy Narrative [Text Block]

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The fund’s investment objective is to seek as high a level of interest income exempt from federal income tax as is consistent with preservation of capital. Under normal market conditions, the fund invests at least 80% of its net assets, plus amounts borrowed for investment purposes, in tax-exempt bonds of any maturity. The fund primarily invests in bonds that are investment grade when purchased, but the fund may also invest up to 35% of its net assets in non-investment grade bonds rated BB or lower by S&P Global Ratings (S&P), Fitch Ratings (Fitch), or Moody’s Investors Service, Inc. (Moody’s), or comparable rating by any nationally recognized statistical ratings organization (NRSRO) or unrated equivalents. The fund may invest in other fixed income securities which include bonds, debt securities and other similar instruments. The fund’s investment policies are based on credit ratings at the time of purchase.

The fund may invest in general obligation bonds, however, in general, the manager favors bonds backed by revenue from a specific public project or facility, such as a power plant (revenue bonds), as they tend to offer higher yields than general obligation bonds. The manager also favors bonds that have limitations on early payoff (call protection), which can help minimize the effect of falling interest rates on the fund’s yield. To the extent that the fund invests in bonds that are subject to the alternative minimum tax (AMT), the income paid by the fund may not be entirely tax-free to all investors. Investments in bonds subject to the AMT will not be counted toward the fund’s 80% investment policy.

The fund may buy bonds of any maturity or duration. The fund may invest heavily in bonds from any given state or region, and may have substantial investments in obligations of certain states and their agencies, instrumentalities, and/or political subdivisions. The fund may engage in derivative transactions that include futures contracts on debt securities and debt securities indexes; options on futures, debt securities, and debt indexes; and inverse floating-rate securities, in each case, for the purposes of reducing risk and/or enhancing investment returns.