EHR interoperability is the ability of different electronic health record systems to exchange, interpret, and use patient data across organizations. When it works, your medical history follows you from your primary care doctor to a specialist to an emergency room, even if each facility uses a completely different software system. When it doesn’t, clinicians end up making decisions with incomplete information, and you end up repeating the same tests or filling out the same forms at every new office.
The Four Levels of Interoperability
The Healthcare Information and Management Systems Society (HIMSS) defines four levels, each building on the one before it.
Foundational interoperability is the simplest: one system can send data and another can receive it. Think of it as being able to pass a file between two computers. The receiving system gets the data but doesn’t necessarily know what to do with it.
Structural interoperability means the format of that data is preserved. Both systems can open the same file types and recognize the basic layout, so the information isn’t garbled in transit.
Semantic interoperability is where things get meaningful. Both systems define clinical concepts the same way. A hemoglobin A1C result recorded at one hospital means exactly the same thing when it arrives at another. Without this level, a lab value from one system might be misread or ignored by another.
Organizational interoperability adds the human layer: governance, privacy policies, consent agreements, and shared workflows that let two institutions actually trust and use each other’s data in practice. Technology alone can’t solve interoperability if the organizations involved haven’t agreed on who can see what, when, and why.
How FHIR Makes Data Exchange Work
The technical standard driving most modern interoperability efforts is FHIR (Fast Healthcare Interoperability Resources), developed by the standards organization HL7. FHIR works by breaking health data into small, discrete pieces called “Resources.” A Patient Resource contains demographics like name, address, and phone number. A Medication Resource holds prescription details. An Observation Resource might carry a single lab result.
This modular approach is what makes FHIR different from older standards that transmitted large, monolithic documents. Instead of sending an entire medical record and forcing the recipient to dig through it, FHIR lets a system request just the specific data it needs. A pharmacy system can pull medication information without downloading a patient’s full surgical history.
FHIR uses the same type of web-based communication (called a RESTful API) that powers most modern apps and websites. That design choice makes it far easier for software developers to build connections between health systems than older, more rigid standards required. Combinations of Resources can be bundled into Implementation Guides tailored to specific use cases, like a provider directory or patient-reported outcomes.
What Data Gets Shared
The U.S. government maintains a standardized set of data categories called the United States Core Data for Interoperability (USCDI) that defines the minimum information EHR systems must be able to exchange. Version 4 includes over two dozen data classes covering the core of a patient’s medical picture: allergies, medications (including dose and fill status), lab results with reference ranges and units, vital signs, immunizations, clinical notes like discharge summaries and progress notes, and problem lists with diagnosis and resolution dates.
It goes well beyond basic clinical data. USCDI v4 also includes health insurance coverage details, care team member names and roles, implantable medical device identifiers, diagnostic imaging reports, and encounter information like visit type and location. Social determinants of health appear throughout, with dedicated elements for things like substance use, physical activity, and housing-related concerns. Patient goals and care preferences, including treatment intervention preferences, are also part of the standard.
Demographics are detailed as well: not just name and date of birth, but previous names, previous addresses, tribal affiliation, occupation, and related persons. The idea is that any system receiving this data has enough context to provide safe, informed care.
The National Framework Connecting Networks
Individual hospitals and health systems often belong to regional or vendor-specific health information networks. The challenge has been getting those separate networks to talk to each other. That’s the problem TEFCA (the Trusted Exchange Framework and Common Agreement) was built to solve.
Created by the Office of the National Coordinator for Health Information Technology, TEFCA establishes a “network of networks” for nationwide health information sharing. The backbone is made up of Qualified Health Information Networks, or QHINs, which serve as central connection points. Each QHIN agrees to the same technical standards and legal terms, so a hospital connected to one QHIN can exchange data with a clinic connected to a different QHIN without needing a custom integration between them.
TEFCA’s goal is to remove the barriers that have historically made it easier to fax a medical record than to send it electronically. It covers providers, patients, public health agencies, and payers under a single set of rules.
Legal Requirements and Penalties
The 21st Century Cures Act made interoperability a legal obligation, not just a best practice. Since October 2022, any practice that interferes with the access, exchange, or use of electronic health information can constitute “information blocking” under federal law.
As of July 2024, the government began enforcing financial penalties for healthcare providers found to have blocked information. The consequences are built into existing Medicare payment programs. Hospitals that commit information blocking lose a portion of their annual payment increase. Clinicians participating in the Merit-based Incentive Payment System receive a zero score on the interoperability performance category, which typically accounts for a quarter of their total score. Accountable care organizations can be barred from the Medicare Shared Savings Program for at least a year.
These rules apply to providers, health IT developers, and health information networks alike. The penalties are calibrated based on factors like the nature of the blocking, how quickly the organization corrected the problem, and how much time has passed.
Where Adoption Stands Today
Progress has been significant but uneven. As of 2025, 76% of U.S. hospitals engage in all four measured interoperability domains: sending, receiving, finding, and integrating patient information into their EHR systems. That number has climbed steadily in recent years, but it still means roughly one in four hospitals isn’t fully participating in electronic data exchange.
The clinical impact of closing that gap is real. A meta-analysis of EHR systems found that electronic records are associated with a 32% reduction in diagnostic errors and a 26% reduction in medication errors compared to paper-based systems. Those benefits depend not just on having an EHR, but on that EHR being able to pull in complete information from other sources. A system that can’t access a patient’s medication list from another provider can’t flag a dangerous drug interaction.
Why Full Interoperability Remains Difficult
The remaining gaps aren’t purely technical. Many health systems still run older software that predates modern standards like FHIR, and upgrading or building bridges to legacy systems is expensive and time-consuming. Even when two systems technically support the same standards, subtle differences in how they categorize or label data can cause mismatches. One system’s “active medication” field might not map cleanly to another’s.
Organizational barriers are equally stubborn. Competing health systems don’t always have strong incentives to make patient transfers seamless, since a patient whose records travel easily is a patient who can more easily leave for a competitor. Privacy regulations, while essential, add complexity: different states have different rules about what data can be shared, who can consent, and how behavioral health or reproductive health records must be handled. TEFCA and the Cures Act are designed to push through these barriers, but aligning thousands of organizations under a single framework takes years of negotiation and implementation.