how can the cost of health insurance decrease a company's income?

so, a company helps pay off people's premiums by paying off a certain percentage. but the insurance cost is rising, so the amount the company pays off for employees is also rising. well, other than the fact that insurance rates exceeding income rates affect a company's income (because of premiums etc), what other evidence can support the fact that health insurance decreases a companys income?
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It's an expense. Aside from the fact that ANY expense rises, there is no other reason an expense decreases income. Income is ONLY decreased when expenses rise.
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