Merritt Personal Lines Manual: Chapter 7 Pre-Existing Conditions

Insurers are allowed to deny coverage for preexisting conditions under group policies. However, insurance companies can impose only one 12-month waiting period for any pre-existing condition treated or diagnosed in the previous six months. If the insured has maintained coverage without a break for more than 62 days, prior health insurance coverage will be credited toward the pre-existing condition exclusion period.

If an employee has been covered under a group policy for at least two years and then changes jobs and is covered under a new employer health plan, the new health plan can't impose another pre-existing condition exclusion period.