Normally to be in the Reserves you must have been resident in the United Kingdom for three years - therefore Expats become exempt on my understanding.
Other exemptions, deferral or revocation can include:
- you have primary parental or care responsibilities
- you are engaged in full-time education or training
- you are self-employed or work in a family-run business which would be seriously harmed by your absence
- you have entered into a contract of employment but have not yet started work and your employer won’t agree to postpone your start date
- other compassionate reasons
Don't forget that call-out is normally for VERY extreme needs - like Gulf Wars, Falklands Wars, World Wars, etc...
LJ