Trailmark Series Trust 485BPOS

Exhibit 99.(g)(4)

THIRD AMENDMENT TO THE CUSTODY AGREEMENT

THIS THIRD AMENDMENT effective as of the last date of the signature block (the “Effective Date”), to the Custody Agreement dated as of January 5, 2021, as amended (the “Agreement”), is entered into by and between TRAILMARK SERIES TRUST (f/k/a IDX FUNDS), a Delaware statutory trust, (the “Trust”), and U.S. BANK NATIONAL ASSOCIATION, a national banking association organized and existing under the laws of the United States of America with its principal place of business at Minneapolis, Minnesota (the “Custodian”).

RECITALS

WHEREAS, the parties have entered into the Agreement; and

WHEREAS, the parties desire to amend the Agreement to reflect the new name of the Trust as Trailmark Series Trust; and

WHEREAS, the parties desire to amend the Agreement to update Exhibit B to:

Reflect the following name change:

Remove the following fund:

WHEREAS, Article XV, Section 15.02 of the Agreement allows for its amendment by a written instrument executed by both parties, and authorized or approved by the Board of Trustees.

NOW, THEREFORE, the parties agree to amend the Agreement as follows:

SIGNATURE BLOCK ON NEXT PAGE

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed by a duly authorized officer on one or more counterparts as of the date and year last written below.

Exhibit B to the Trailmark Series Trust Custody Agreement

Name of Series

IDX Adaptive Opportunities Fund

Based upon an annual rate of average daily market value of all long securities and cash held in the portfolio*:

0.50 basis points

$ 4,800 - Minimum annual fee per fund

Plus portfolio transaction fees

Portfolio Transaction Fees

A transaction is a purchase/sale of a security, free receipt/free delivery, maturity, tender or exchange.

Miscellaneous Expenses

All other miscellaneous fees and expenses, including but not limited to the following, will be separately billed as incurred: expenses incurred in the safekeeping, delivery and receipt of securities, shipping, transfer fees, deposit withdrawals at custodian (DWAC) fees, SWIFT charges, negative interest charges and extraordinary expenses based upon complexity.

Additional Services

Additional services not included above shall be mutually agreed upon at the time of the service being added. In addition to the fees described above, additional fees may be charged to the extent that changes to applicable laws, rules or regulations require additional work or expenses related to services provided (e.g., margin management services, securities lending services, compliance with new SEC rules and reporting requirements).

Fees are calculated pro rata and billed monthly.

*Subject to annual CPI increase - All Urban Consumers - U.S. City Average" index, provided that the CPI adjustment will not decrease the base fees (even if the cumulative CPI rate at any point in time is negative).

Additional Global Sub-Custodial Services Annual Fee Schedule

* Includes Ivory Coast, Mali, Niger, Burkina Faso, Senegal, Guinea Bissau, Togo and Benin.

Global Custody Base Fee

$500 monthly base fee of per fund will apply. If no global assets are held within a given month, the monthly base charge will not apply for that month. "Safekeeping and transaction fees are assessed on security and currency transactions.”

Miscellaneous Expenses