Imaging & Lab Test Billing Errors: 8 Mistakes to Catch in 2026

The 8 Errors to Check on Every Imaging or Lab Bill

Before diving into each item, get one thing in hand: your itemized bill. A summary statement showing only totals isn't enough. You're legally entitled to an itemized statement from any hospital or provider. Request it in writing, and ask for the CPT and HCPCS codes for every line — not just plain-language descriptions. Then pull your Explanation of Benefits (EOB) from your insurer and compare the two documents side by side. If you need help reading an EOB, our post on Medicare Summary Notice vs. Commercial EOB: How to Read Each in 2026 explains the key fields.

1. Duplicate charges for the same test on the same date
2. Unbundling — billing panel components separately instead of as a panel
3. Wrong CPT code (upcoding to a higher-complexity or higher-cost imaging variant)
4. Contrast vs. no-contrast imaging billed incorrectly
5. Out-of-network balance billing for radiology or lab services at an in-network facility
6. Lab or imaging billed without a valid physician order (no documented medical necessity)
7. Facility fee charged in addition to a professional fee — without disclosure
8. Charge doesn't match the hospital's publicly posted price transparency file

Errors 1–2: Duplicates and Unbundling

Duplicate charges occur when the same CPT code appears more than once on the same date of service with no clinical justification. They happen when procedures get entered twice, when multiple departments each bill for the same service, or when system glitches create duplicate records. On an imaging or lab bill, look for any five-digit CPT code appearing more than once on the same date. Some code pairs represent the same service at different levels — for example, 71046 (2-view chest X-ray) and 71048 (4-view chest X-ray). If both appear on the same day and you only had one study, one is likely wrong.

There are legitimate reasons for a test to be repeated the same day, but the bill must show it correctly. CPT Modifier 76 indicates "repeat procedure by same physician" and distinguishes between duplicate services and repeated services. CPT Modifier 77 indicates "repeat procedure by another physician" when a second physician repeats a service on the same day. CPT Modifier 91 is used for a repeat clinical diagnostic laboratory test when it is necessary to repeat the same test on the same day to obtain multiple results. If you see the same code twice with no modifier 76, 77, or 91 attached, that's a strong red flag worth disputing.

Unbundling is the reverse problem: a lab panel or combined imaging study gets split into individual component codes, each billed separately at a higher combined cost than the panel price would be. Incorrect coding — including using incorrect procedure codes or modifiers — can result in improper payments. CMS maintains the National Correct Coding Initiative (NCCI), which defines which codes must be bundled together and cannot be billed separately. The NCCI is a CMS program, and its policies and edits represent CMS national policy. If your bill shows individual CBC components (e.g., hematocrit, hemoglobin, platelets) rather than a single comprehensive blood count panel code, ask the billing department to explain why the panel wasn't used.

Errors 3–4: Wrong CPT Codes and Contrast Errors

Imaging is particularly vulnerable to CPT code mismatches because many studies have multiple variants — with contrast, without contrast, or both — and each maps to a different code at a different price. Contrast studies reimburse more — which is exactly why they are scrutinized more. If you had a plain MRI without contrast but your bill shows a code for a contrast study, you've been overbilled. Check your radiology report (you can request it from the hospital's health information management department) and compare the study description to the CPT code on your bill.

A related pattern involves "upcoding" — substituting a higher-complexity code for what was actually performed. According to HHS-OIG hospital audit findings, the most common error type for hospital outpatient claims was reporting incorrect HCPCS/CPT codes. The second most common error was incorrect usage of bypass modifiers, such as modifiers 59, XE, XS, XU, and XP. For a deeper look at how upcoding works and how to spot it, see our guide on What Is Upcoding? How Hospitals Inflate Your Bill — and How to Spot It.

For radiology specifically, the professional component (the radiologist reading the scan) and the technical component (the equipment and staff performing the scan) are sometimes billed separately using modifier -26 (professional) and modifier -TC (technical). Both together equal the "global" code. Hospitals often bill separately for the physician's work (professional fee) and the hospital's resources (facility fee) — this is legal — but when the same CPT code appears twice with identical charges, that is still duplicate billing. Make sure you're not paying both the global code and also a separate professional-component charge, which would amount to paying twice for the radiologist's reading.

Error 5: Out-of-Network Balance Billing for Radiology and Labs

This is one of the most financially damaging errors — and one of the clearest federal protections available to you. The No Surprises Act, which became effective on January 1, 2022, is federal legislation designed to protect patients from surprise medical billing that occurs when a patient receives services from a facility or provider which, unknown to the patient, is outside of his or her health plan's network, resulting in unexpected out-of-network charges. Critically for imaging and lab patients, the federal legislation also applies to non-emergency care provided at in-network hospitals, where patients receive services from out-of-network providers, such as clinical laboratories.

In these cases, the most those providers may bill you is your plan's in-network cost-sharing amount — and this applies to emergency medicine, anesthesia, pathology, radiology, laboratory, neonatology, assistant surgeon, hospitalist, or intensivist services. These providers can't balance bill you and may not ask you to give up your protections not to be balance billed. The applicable federal rules are codified at 45 CFR § 149.420 (limits on out-of-network charges at in-network facilities) and 45 CFR § 149.410 (limits on balance billing for emergency services).

Under the No Surprises Act's regulatory definitions, a "visit" at a health care facility includes imaging services, laboratory services, and preoperative and postoperative services, regardless of whether the provider furnishing such items or services is physically at the facility. This means even off-site lab processing connected to your in-network visit is covered. If you receive a balance bill from a radiologist or an outside lab for services that were part of an in-network hospital visit, you can dispute it under the No Surprises Act. See our overview at Balance Billing & the No Surprises Act: Know Your Rights in 2026.

Error 6: No Valid Physician Order (Medical Necessity)

Every diagnostic imaging study and lab test billed to Medicare or a private insurer is supposed to be ordered by a treating physician and supported by documented medical necessity. CMS gives the responsibility of documenting medical necessity to the referring physician as part of the Medicare Conditions of Participation at 42 CFR § 410.32, and those conditions state that all diagnostic tests must be ordered by the treating physician. When that order or documentation is missing, the charge is potentially invalid.

Insufficient documentation occurs when the provided documentation does not adequately support the billed services, making it challenging to verify that the services were necessary and delivered as claimed. Medical necessity errors arise when the submitted documentation fails to justify the necessity of the services provided, leading to payments for services that may not meet coverage criteria. As a patient, you can request copies of your physician's orders for any imaging or lab test. If you were billed for a test you don't remember your doctor ordering, ask the billing department to show you the order. If they can't, that charge should be disputed.

This also applies to repeat tests. CPT Modifier 91 (Repeat Clinical Diagnostic Lab Test) must be supported with clear documentation showing that repeat testing was necessary due to a new clinical finding or intervention. If your bill shows the same lab test twice in one day and no Modifier 91 is present — or if there's no clinical reason documented for the repeat — that's a billing error worth challenging. For a practical walkthrough of how to spot and dispute phantom or unsupported charges, see Phantom Charges on Your Hospital Bill: How to Spot and Dispute Them in 2026.

Errors 7–8: Facility Fees and Price Transparency Mismatches

Hospital-owned imaging centers and labs often charge a facility fee on top of the professional fee from the physician reading or interpreting the test. This practice is legal, but the fee must be disclosed, and patients have had surprise facility fees land on bills for what felt like a simple outpatient lab draw. Under the law, health care providers need to give patients who don't have certain types of health care coverage an estimate of the bill for medical items and services before those items or services are provided — and you have the right to receive a Good Faith Estimate for the total expected cost of any non-emergency items or services upon request or when scheduling. Under 45 CFR § 149.610, laboratories and imaging centers that meet the definition of "facility" must provide a Good Faith Estimate to uninsured or self-pay patients.

For error 8, hospitals are now required by federal regulation to publish their standard charges — including individual imaging and lab CPT codes — in a machine-readable file. The hospital price transparency requirements are codified at 45 CFR Part 180 and require most hospitals to make public their standard charges online. The required machine-readable file must contain gross charges, discounted cash prices, payer-specific negotiated charges, and de-identified minimum and maximum negotiated charges. In the CY2026 OPPS/ASC Final Rule, CMS finalized the addition and removal of several required data elements from the CMS templates that are effective January 1, 2026, with CMS enforcement beginning April 1, 2026.

That file is publicly accessible on every hospital's website — look for a "Price Transparency" link in the footer, as required by 45 CFR § 180.50(d)(6). Search for the CPT code on your bill in that file and compare the "payer-specific negotiated charge" for your insurer against what your insurer's EOB shows as the allowed amount. A significant gap between those figures — especially if you're being asked to pay based on a gross charge rather than the negotiated rate — is a charge worth questioning. Our companion post on What 'Adjustments' on a Hospital Bill Really Mean in 2026 explains how negotiated rates and adjustments should flow through your statement.

Billing Error Reference Table for Imaging and Lab Charges

The table below summarizes each error type, how it typically appears on a bill, and what to look for when you review your itemized statement.

How to Dispute an Imaging or Lab Billing Error

Once you've identified a potential error, act in writing. Call the hospital billing department to flag it verbally first — many errors are resolved quickly at this stage — but always follow up with a written dispute letter sent by certified mail or submitted through the hospital's patient portal. Include the specific line item (CPT code, date of service, charge amount), the reason you believe it's wrong, and any supporting documentation (your radiology report, the physician's order, the Good Faith Estimate, or the price transparency file entry).

If the billing department doesn't resolve it, escalate to the hospital's patient advocate or financial counselor. For out-of-network balance billing violations under the No Surprises Act, you can file a complaint directly with CMS at 1-800-985-3059 or at cms.gov/nosurprises. If you're uninsured or self-pay and your final bill exceeds the Good Faith Estimate by more than $400, you can initiate the Patient-Provider Dispute Resolution process under 45 CFR § 149.620. The primary consequence for failing to provide a sufficient Good Faith Estimate is that a patient may force the Selected Dispute Resolution process and likely avoid paying his or her full bill if the actual charges are more than $400 over the expected charges.

HHS-OIG's ongoing series of hospital compliance reviews focuses on hospitals with claims that may be at risk for overpayments, with prior OIG reviews and investigations having identified areas at risk for noncompliance with Medicare billing requirements. That oversight framework benefits all patients: hospitals that face federal audit pressure have greater incentive to correct errors promptly when patients raise them. If you need to understand the federal dispute resolution process in more depth, our post on What the Federal IDR Process Actually Means for Your Medical Bill in 2026 walks through the full mechanics.

About VerifyDoc: We help patients identify errors and overcharges on medical bills. We publish guides on hospital billing, the No Surprises Act, and disputing medical charges, updated as federal and state rules change.