The minimum age at entry for a policy will vary based on the insurer’s terms and conditions. The eligibility criteria of a policy can be found in the policy brochure.In most cases, the policyholder must be over 18 years of age. Some pension plans set the minimum entry age at 30 years. In case of some immediate annuity plans intended for senior citizens, the entry age could be as high as 55 years. Based on the type of plan chosen, the entry age criteria will differ for various pension plans.