Reasonable and customary (R&C), also called usual and customary or prevailing rate, refers to the maximum amount an insurer considers appropriate for a particular health service in your geographic area. Insurance plans reimburse based on the R&C amount, not necessarily what the provider charges. If your physiotherapist charges $110 per session but your plan's R&C limit is $85, the insurer calculates your reimbursement based on $85 — you pay the $25 difference plus your co-insurance share. R&C amounts are determined by surveying what practitioners in your region typically charge for comparable services. They are updated periodically but may lag behind actual market rates. Some plans use a fixed fee schedule instead of R&C, which can be even more restrictive.