As joiedevie99 said , to be a coach at a USEF show you have to be an active USEF member.
GR202-1 To be eligible to participate as a rider, driver, handler, vaulter, longeur, owner, lessee, agent, coach, or trainer at Federation Licensed Competitions, persons must be Members of the Federation as provided in Bylaw 212.
No organization, other than the Federation and its Recognized Breed and Discipline Affiliates, may require mandatory membership or a non-member fee as a condition of participation in a Federation Licensed Competition. (See GR1210.12 for further information regarding the collection of mandatory participation fees
at Federation Licensed competitions).
GR202-7 To be eligible to compete at Federation Licensed Competitions, coaches, trainers, and legal guardians signing as coaches or trainers on behalf of their minors must be Senior Active Members in good standing, as defined herein.
Bylaw 211 - Designation
Members consist of those persons who have joined the Federation in one or more of the membership categories as provided in the Rules. All members in good standing, except Non-Competing Members, and Individual Group Members,shall be eligible to participate in all classes and levels at Federation Licensed Competitions as provided in Bylaw 203.** Each member will be required upon joining or renewing to designate a primary Breed/Discipline affiliation within the Federation
(and may designate one or more secondary Breed/Discipline affiliation for informational purposes only). The record datefor designations shall be November 30, with the primary designations of all Senior Active Members made since December 1 of the preceding year to be counted. A Senior Active Member will be deemed to continue their primary and secondary affiliation designations unless prior to the record date such Senior Active Member notifies the Federation in writing of a change
If you want to participate in USEF rated shows you have to join USEF, take the Safe Sport training etc…