Exhibit (h)(22)

Calamos Advisors LLC

2020 Calamos Court

Naperville, Illinois 60563-1493

April 8, 2026

Calamos Advisors Trust

2020 Calamos Court

Naperville, Illinois 60563-1493

Ladies and Gentlemen:

Calamos Advisors LLC (“Calamos Advisors”) hereby undertakes as follows:

In the interest of limiting the expenses of the Calamos U.S. Equity Autocallable Income VIP Fund, a series of Calamos Advisors Trust (the “Fund”), Calamos Advisors undertakes to reimburse the Fund to the extent, but only to the extent, that the annualized expenses of Class I of the Fund, as a percentage of the average net assets of such class of shares exceed 0.90%, and the annualized expenses of Class II of the Fund, as a percent of the average net assets of such class of shares exceed 1.15%, through December 1, 2029. This calculation will exclude taxes, interest, short interest, short dividend expenses, brokerage commissions, acquired fund fees and expenses, foreign tax reclaim expenses, and extraordinary expenses (as determined in the discretion of Calamos Advisors) such as litigation costs, but will include fees paid to Calamos Advisors.ⁱ

The amount of the expense reimbursement to the Fund (or any offsetting reimbursement by the Fund to Calamos Advisors) shall be computed on an annual basis, accrued daily and paid monthly. Calamos Advisors may recapture previously waived expense amounts within the same fiscal year for any day where the Fund’s expense ratio falls below the contractual expense limit up to the expense limit for that day. This undertaking shall be binding upon any successors and assigns of Calamos Advisors.

ⁱ Accrual of fund expenses and any reimbursement occurs on a daily basis in conjunction with the striking of the NAV. All operating expenses, excluding sub-TA expenses, as applicable, but including the management fee, are calculated based on the total assets of the fund. Any sub-TA expenses are calculated on the total assets of the fund. Any reimbursement is then calculated at the fund level. The fund level expenses, net of any reimbursement, are then allocated to each share class based on class assets. This approach ensures that all operating expenses and reimbursements are applied to all shareholders equally. Class specific 12b-1 fees are then applied to each share class, except for those share classes that have no 12b-1 fees. The class specific 12b-1 fees, and, if any, sub-TA expenses account for the difference in expense ratios among classes on a daily basis.