Currently, there aren't any laws that set specific restrictions or establish guidelines for how long your employee has to wait before becoming eligible to participate in your health plan. Although you can choose any limit you want (or at least any limit your insurer offers), the most common time limits are:
Which period should you choose? There are several factors that come into play in making your decision which eligibility period to choose. They are:
Should you have age limits? Some employers place maximum and minimum age limits on health plan eligibility in order to keep costs down. This decision may well be driven by your health insurance company. Talk to them about whether they use maximums or minimums.
As for the minimum age, there are no laws telling you what you have to do. Many employers don't have a minimum age; many of those that do choose age 18.
Age maximums are a little trickier. Generally, an employer that places age
maximums on employees runs the risk of violating the age discrimination laws. Of
course, if you have fewer than 20 employees, the federal age
discrimination laws do not apply to you (although state antidiscrimination
laws might). As a consequence, if you have fewer than 20 employees, you may not
have to offer employees who work past age 65 coverage on the same basis as other
employees. Age maximums are much more common in the area of employees'
dependents (for example, children are no longer eligible once they reach age
22). Many health plans do require that those employees eligible for Medicare
(i.e., age 65 or over) must take advantage of it.