Well, this depends on the circumstances. Typically, you can only add dependents to an eisting Small Business plan during the 30 day open enrollment period. However, if your son has been insured on a different group plan, perhaps through your spouse, or under an individual or state-sponsored health plan, and this coverage has been terminated involuntarily, you can add your son at any time. The application to add your son to the group plan must be submitted within 30 days of the termination date of his prior coverage, if this is applicable. Newborns are automatically insured under a group plan for 30 days following birth, but formal inclusion on the policy must be made within 30 days of birth