July 21, 2020 State Street Bank and Trust Company One Heritage Drive North Quincy, Massachusetts 02171 Location Code: OHD0310 Attention: Russell M. Donohoe Re: Transfer Agency and Service Agreement – New Portfolios Ladies and Gentlemen:

July 21, 0000

Xxxxx Xxxxxx Bank and Trust Company

Xxx Xxxxxxxx Xxxxx

Xxxxx Xxxxxx, Xxxxxxxxxxxxx 00000

Location Code: OHD0310

Attention:  Xxxxxxx X. Xxxxxxx

Re: Transfer Agency and Service Agreement – New Portfolios

Ladies and Gentlemen:

Please be advised that the undersigned Trust has established three (3) new series of shares to be known as:

American Century ETF Trust – Avantis Core Fixed Income ETF

American Century ETF Trust – Avantis Short-Term Fixed Income ETF

American Century ETF Trust – Avantis Core Municipal Fixed Income ETF (the “New Portfolios”)

In accordance with Section 12, the Additional Trusts and Portfolios provision, of the Transfer Agency and Service Agreement dated as of January 9, 2018 (the “Transfer Agency Agreement”) by and among each Trust party thereto and State Street Bank and Trust Company, the undersigned Trust hereby requests that your bank act as Transfer Agent for the respective New Portfolios under the terms of the Transfer Agency Agreement. In connection with such request, the undersigned Trust hereby confirms to you, as of the date hereof, its representations and warranties set forth in Section 4 of the Transfer Agency Agreement. Capitalized terms used herein without definition shall have the meanings ascribed to them in the Transfer Agency Agreement.

Kindly indicate your acceptance of the foregoing by executing this letter agreement and returning a copy to the Trust.

Sincerely,

    American Century Investment Management, Inc. on behalf of

    American Century ETF Trust – Avantis Core Fixed Income ETF

    American Century ETF Trust – Avantis Short-Term Fixed Income ETF

    American Century ETF Trust – Avantis Core Municipal Fixed Income ETF

By:    /s/ Xxxx X. Xxxxx

Name:    Xxxx X. Xxxxx

Title:    Vice President, Duly Authorized

Agreed and Accepted:

STATE STREET BANK AND TRUST COMPANY

By:    /s/ Xxxxx Xxxxxx

Name:    Xxxxx Xxxxxx

Title:    Senior Vice President

Effective Date:    July 21, 2020

American Century Investments

P.O. Box 410141, 0000 Xxxx Xxxxxx    xxxxxxxxxxxxxxx.xxx    Corporate Headquarters: Kansas City, MO

Xxxxxx Xxxx, XX 00000-0000    800-345-2021 or 816-531-5575