How small does a company have to be to NOT offer health/medical insurance?

I always thought that if a company has 20 or more employees at a SINGLE location, they have to offer health/medical insurance to ALL the eployees. I work in a store that employs 25 people, and only the managers are offered insurance.
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There is no federal law mandating that small employers have to offer health insurance, or even pay for a portion of it. It is an employer's choice whether or not it is offered. State law will dictate eligibility rules, however. Typically, an employer can set up eligibilty to exclude employees that are part time, are part of a CBA or Union or those that have not met some time worked criteria. (Must work 90 days before eligible, for example.) Your employer should have given you an employee benefits handbook that explains the eligibility rules for your particular situation.
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