Can a Small Business Provide Health Insurance for Employees in Multiple States?

I am Secretary/Treasurer of a small nonprofit. I have three employees in three states. In the past I have paid (directly to the provider) 100 percent of the cost of each employees health insurance. The employee identified the insurer, who was then compensated directly for the full cost of the employees coverage, directly from our corporate account. I am told this is no longer legal but I have no idea how to provide my employees with coverage as they are each in a different state.