The following people are entitled to register to vote as service electors:
serving members of the armed forces and their spouses or civil partners (for whom the entitlement exists as an alternative to registering as civilian electors if resident in the UK)
British Council staff and Crown Servants in posts abroad and their spouses or civil partners
by completing and submitting the appropriate Service Declaration at www.gov.uk/register-to-vote
The Declaration, in relation to serving members of the armed forces and their spouses or civil partners, lasts for 5 years and then lapses if not renewed by the elector. The ERO is obliged to send a reminder and a new application form to the elector between 57 and 58 months from the date on which the entry on the Register took effect. Crown Servants and British Council staff declarations last for 12 months then lapse if not renewed. The ERO however is obliged to send a reminder and new application form between 9 and 10 months from the effective date.