What should i do with a refund check received from a health insurance that my former employer paid for?

I worked for a small company and they decided to finally get health insurance for the employees. The company paid for the insurance thus no money was taken from my check. I was let go from work when the policy went into effect.
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All employers who provide insurance for their employees either pay the insurance premium in full or have the employees pay a portion of it. If you received the check for reimbursement of a health bill, you should keep it. However, if you received reimbursement for the premium that was paid by your employer, you need to give it to your former employer. If it was for the premium, they will find out eventually.
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