COLUMBIA THREADNEEDLE/CWAM LETTERHEAD] May 1, 2019

[COLUMBIA THREADNEEDLE/CWAM LETTERHEAD]

May 1, 2019

Columbia Acorn Trust

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Suite 3000

Chicago, Illinois 60606

Ladies and Gentlemen:

Columbia ▇▇▇▇▇▇ Asset Management, LLC (“CWAM”) hereby contractually undertakes as of the date hereof with respect to Columbia Acorn International (the “Fund”), a series of Columbia Acorn Trust (the “Trust”), to waive fees and reimburse certain expenses of the Fund, through April 30, 2020, such that total Fund ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, and interest and fees on borrowings, if any) do not) do not exceed the annual rates of:

• 1.24% of the Fund’s average daily net assets attributable to Class A shares;

• 0.99% of the Fund’s average daily net assets attributable to Adviser Class shares;

• 1.99% of the Fund’s average daily net assets attributable to Class C shares;

• 0.99% of the Fund’s average daily net assets attributable to Institutional Class shares;

• 0.92% of the Fund’s average daily net assets attributable to Institutional 2 Class shares;

• 0.88% of the Fund’s average daily net assets attributable to Institutional 3 Class shares; and

• 1.49% of the Fund’s average daily net assets attributable to Class R shares; and

This agreement may not be modified or terminated without the approval of the Fund’s Board of Trustees and CWAM.

This undertaking shall be binding upon any successors and assignees of CWAM.

Very truly yours,

COLUMBIA ▇▇▇▇▇▇ ASSET MANAGEMENT, LLC

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Chief Financial Officer

Agreed and accepted by

COLUMBIA ACORN TRUST, on behalf of its series Columbia Acorn International

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Co-President