An HSA-compatible health plan is a health insurance plan that meets the guidelines set by the IRS regarding deductibles, out-of-pocket expenses and acceptable coverage. The health plan cannot provide benefits before the deductible is met, except for preventive care services. All co-payments or co-insurance (e.g. prescription drug costs) must be counted toward the deductible and out-of-pocket limits. Co-payments required before a deductible is met can prevent the plan from being an HSA-compatible health plan.