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American Century Mutual Funds, Inc | BALANCED FUND

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Target Maturities Trust | ZERO COUPON 2025 FUND

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century California Tax-Free and Municipal Funds | CALIFORNIA TAX-FREE MONEY MARKET FUND

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

American Century Quantitative Equity Funds Prospectus | UTILITIES FUND

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None

AMERICAN CENTURY MUNICIPAL TRUST | TAX-FREE MONEY MARKET FUND

Prospectus [Line Items]

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Supplement to Prospectus [Text Block]

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Prospectus Supplement Supplement dated August 1, 2024

Balanced Fund

(Prospectus dated March 1, 2024)

Zero Coupon 2025 Fund

(Prospectus dated February 1, 2024)

California Tax-Free Money Market Fund

(Prospectus dated January 1, 2024)

One Choice© Portfolio: Very Conservative n One Choice© Portfolio: Conservative

One Choice© Portfolio: Moderate n One Choice© Portfolio: Aggressive

One Choice© Portfolio: Very Aggressive

(Prospectus dated December 1, 2023)

Utilities Fund

(Prospectus dated November 1, 2023)

Tax-Free Money Market Fund

(Prospectus dated October 1, 2023)

Beginning October 2024, the total eligible investments required to qualify for a waiver of the annual account maintenance fee will change from $10,000 to $25,000. Such fee will also be waived for any accounts for which the shareholder has elected to receive electronic delivery of all fund/account documents.

As a result, the Shareholder Fees table in each prospectus is updated to reflect the following:

	Investor Class	All other classes
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $25,000 or shareholder has elected electronic delivery)	$25	None