AR 600-8-22 opens the Expert Soldier Badge to all Regular Army, ARNG/ARNGUS and USAR Soldiers except those in infantry, Special Forces and medical career management fields. Candidates must meet prerequisites set by TRADOC, and only the CG, U.S. Army Center for Initial Military Training may authorize testing or award the badge.
The Expert Soldier Badge is governed by AR 600-8-22, the Army's military awards regulation, at paragraph 8-14.
Eligibility is defined by exclusion rather than by a list of qualifying jobs. The regulation states:
all Regular Army, ARNG/ARNGUS, and USAR Soldiers except those in infantry, SF, and medical CMFs can compete for the ESB
AR 600-8-22, para 8-14a
Those three excluded career fields have their own badges: infantry and Special Forces Soldiers compete for the Expert Infantryman Badge, and medical CMFs for the Expert Field Medical Badge.
Beyond that basic eligibility, the regulation does not itself list the testing standards. It delegates them:
Soldiers must meet prerequisites established by TRADOC
AR 600-8-22, para 8-14b(2)
So the current event list, standards and retest rules come from TRADOC, not from AR 600-8-22. Check with your S1 or the testing unit for the version in force when you test.
Two limits are worth knowing before you plan around the badge:
The ESB may not be awarded retroactively
AR 600-8-22, para 8-14b(5)
Foreign military personnel may be awarded the ESB in accordance with AR 600-8-22, paragraph 8-4.