I keep seeing that a health insurance STIPEND is taxable income, and that health insurance reimbursements are NON-taxable. What I can't find is where the IRS says this.

I read all over the place that if the employer provides a STIPEND for health insurance that it is taxable.  I believe this, but I cannot find the reference to this on the IRS website.  

I have small business owners arguing with me, saying that they offer STIPENDS, and their employees don't pay tax on it.  They are not offering reimbursements.  

Please point me to the actual IRS reference for this taxable income.