Reasonable and customary charges for health insurance are based on benchmark pricing data that your insurer applies to each service: typically a percentage of what Medicare pays, a figure drawn from a claims database, or, in certain out-of-network situations, a rate set by federal law. That benchmark is then adjusted for the geographic area where you received care and filtered through the specific terms of your plan.
If the provider charges more than the benchmark, the insurer pays up to its limit and the balance can land on you. Knowing which inputs drive that number is the difference between an unexpected bill and one you saw coming.
How Insurers Calculate the Number
Most insurers rely on reference-based pricing. Rather than paying whatever a provider bills, the insurer compares the charge against a benchmark built from large datasets of claims and reimbursement rates.
Two sources do most of the work. The first is the Medicare fee schedule. An insurer often sets its allowed amount as a percentage of what Medicare would pay for the same service. If Medicare reimburses $1,000 for a procedure and the plan pays 150% of Medicare, the allowed amount is $1,500. The second is private claims databases, which aggregate what hospitals, outpatient centers, and physician offices have actually been paid for similar services. These databases refine the benchmark by reflecting real market payments rather than list prices.
The gap this creates is the practical problem. When a provider’s charge sits well above the insurer’s reference price, and there is no pre-negotiated contract between them, you can be balance billed for the difference.
Why Your Location Changes the Number
Medical prices are not uniform across the country, and the “reasonable” figure moves with them. Insurers analyze regional claims data and apply geographic adjustment factors that account for provider costs, wages, and rent.
Many of these adjustments trace back to the Geographic Practice Cost Indices published by the Centers for Medicare and Medicaid Services. A procedure the insurer considers reasonable at $5,000 in a high-cost metropolitan area might be reimbursed at $3,500 in a smaller town where provider expenses are lower.
How finely an insurer slices the map matters. Some use state-wide averages; others break pricing down by zip code. If you live near a border between pricing regions and seek care on the higher-cost side, your insurer may reimburse at the lower-cost benchmark, leaving you to cover the gap.
How Your Plan’s Terms Shape the Limit
Two policies looking at the same bill can produce different “reasonable and customary” numbers because each plan carries its own formula. Insurers build those formulas from historical claims data, provider contracts, and actuarial models.
The policy type is a major variable. Employer-sponsored plans often negotiate lower rates with providers, which shifts the thresholds they use for out-of-network comparisons. High-deductible health plans may apply more restrictive calculations in line with their lower premiums, while higher-premium comprehensive plans tend to allow broader reimbursement.
The service matters too. Routine care such as diagnostic tests and preventive screenings has well-defined reimbursement rates. Specialized surgeries or experimental therapies show wider pricing variability, so the gap between what a specialist charges and what the insurer deems reasonable can be larger.
When Federal Law Sets the Benchmark Instead
For certain out-of-network services, federal law overrides the insurer’s usual calculation. The No Surprises Act, enacted in late 2020 and effective in 2022, protects patients from surprise bills in specific situations such as emergency care and some services delivered at in-network facilities by out-of-network clinicians.1CMS. Ending Surprise Medical Bills
In those situations, the insurer must use the qualifying payment amount as the benchmark. That amount is generally the median rate the insurer pays in-network providers for the same or similar service in the same geographic area.2Office of the Law Revision Counsel. 42 U.S.C. § 300gg-111
One boundary worth knowing: if your coverage comes through an employer, the Employee Retirement Income Security Act (ERISA) is often the controlling law, and it typically preempts state insurance rules for self-funded employer plans where the employer pays claims directly rather than purchasing traditional insurance.3Office of the Law Revision Counsel. 29 U.S.C. § 1144 State surprise-billing or consumer-protection statutes you might otherwise expect to help may not apply to that type of plan.
What to Do If You’re Billed the Difference
Start with an internal appeal to your insurer. Federal rules give the company set timeframes to respond: generally 30 to 60 days for a claim that has already been paid or denied, and 72 hours for urgent medical situations.4Cornell Law School. 29 C.F.R. § 2560.503-1
If the internal appeal does not resolve the dispute, federal law gives many policyholders the right to an external review.5Office of the Law Revision Counsel. 42 U.S.C. § 300gg-19 An independent organization looks at whether the insurer followed the plan’s terms and the law when it set the reimbursement amount.
Outside the appeals process, you have other ways to reduce what you owe:
- Negotiate directly with the provider for a reduced balance.
- Ask the provider’s billing office for a payment plan.
- Work with a patient advocate who handles insurance disputes.
Deadlines on appeals are tight, so act as soon as the explanation of benefits arrives rather than waiting for a collection notice.