Payment Integrity Infrastructure

Verify before payment. Prove after payment.

Healthcare pays first and determines afterward whether the payment was correct. We create verifiable evidence at the moment care happens, bind it to the payment decision that follows, and preserve it so any reviewer can check the result years later without trusting us.

Working implementation. Record format frozen and published. Verified across 2,080 independent checks with zero failures, reproducible on a machine that has never contacted our systems.

CAPTURE.
VERIFY.
ATTEST.
PROVE.
$28.83B
Medicare fee-for-service improper payments, FY2025, at a 6.55 percent rate
75.5%
of skilled nursing improper payments are insufficient documentation, not fraud
1 million+
stolen Medicare identities used in Operation Gold Rush, $10.6B in claims
24.12%
improper payment rate for durable medical equipment, the highest of any claim type
Verify It Yourself

Do not take our word for any of this.

The verifier is public, open source and offline. Clone it, build it, and check our evidence on a machine that has never contacted us. Then alter a field and watch it fail. Both sessions below are real output from that tool, replayed exactly as recorded.

You do not have to install anything to do it. The same verifier runs inside your browser on the page below, on real signatures, with no request made to us.

Run the verifier in your browser

session 1   verify an episode, then break it
$ git clone https://github.com/med-xt/hpx-verifier $ cd hpx-verifier && go build -o verify ./cmd/verify $ ./verify --bundle conformance/bundle-valid.json \ --keys conformance/keys.json VERIFIES 6 records, episode ep_conformance_0001 chain intact, every record links to its predecessor every record included under the published log root every signature verifies over the canonical payload // now change one field in the discharge record $ sed 's/"nights": 3/"nights": 2/' \ conformance/bundle-valid.json > tampered.json $ ./verify --bundle tampered.json --keys conformance/keys.json DOES NOT VERIFY 6 records, 2 problems record 0 (discharge.proof): DIGEST_MISMATCH record 0 (discharge.proof): SIG_INVALID
session 2   we rewrite our own log, and get caught
// Monday. The log publishes a checkpoint: 12 records. // A witness keeps its own copy. In this demo we hold its key. // Tuesday. Eight more records. The log proves the new tree // grew from the one the witness already holds. $ verify --checkpoint tuesday.checkpoint \ --against monday.checkpoint \ --proof tuesday.proof.json --keys keys.json \ --log-key k-log-001 --witnesses 1 checkpoint tuesday.checkpoint origin medxt-evidence/demo size 20 records root sha256:9112a80d91a44787e29e6c2de790676a... time 2026-10-06T09:00:00.000Z signed by k-log-001#1 The evidence log signed by k-wit-001#1 A witness, key held by MedXT in this demo earlier 12 records at 2026-10-05T09:00:00.000Z CONSISTENT the log of 20 records contains the log of 12, unchanged ANCHORED 1 independent signature, as required exit=0 // Wednesday. We remove one record and rebuild the log. // We hold the real signing key. Everything inside it verifies. $ verify --checkpoint wednesday-rewritten.checkpoint \ --against tuesday.checkpoint \ --proof wednesday.proof.json --keys keys.json checkpoint wednesday-rewritten.checkpoint size 19 records signed by k-log-001#1 The evidence log earlier 20 records at 2026-10-06T09:00:00.000Z INCONSISTENT the log shrank from 20 to 19 exit=1
It is a second implementation, not ours twice Written in Go from the published specification, sharing no code with our reference implementation and using a different post-quantum cryptography library. If the two disagree, one of them is wrong. That is why it is public.
It makes no network call No service, no account, no licence check. The structural checks depend only on the Go standard library, so it runs on a locked down machine with no package manager.
The sample data is synthetic No real beneficiary, provider, encounter or claim. The episode never happened. It exists so you can watch verification succeed, then watch it fail.
It names what failed Not a boolean. Every problem identifies the record by its position in the chain and the specific check that failed, because the question is never just whether evidence is valid.
github.com/med-xt/hpx-verifier
Apache License 2.0 covers the verifier software. The format specification and the conformance vectors are published. The capture adapters and the record production path are not.

Both sessions are transcripts of the published verifier running against synthetic data. Session one is the check most people expect: alter a field, the digest and the signature both fail. Session two is the one that matters more, because it is the case where we are the adversary. We hold the signing key, we rebuild our own log, and a witness that keeps its own record of what it last endorsed refuses to co-sign the result. The mechanism is built and tested. The witness key in this demonstration is still held by us, so until an outside party holds one we do not claim the log is independently anchored. That is a deployment step, not a software one, and we would rather say so here than have you find it later.

The Problem

The evidence is assembled years later, by the party being paid.

A provider makes an assertion. Money moves on that assertion. Years afterward, a reviewer has to determine whether it was true, using records reconstructed after the fact by the party with an interest in the outcome.

Every control in use today works downstream of that. Analytics, audit contractors and claims intelligence all operate on data whose origin cannot be independently checked. They can establish that a claim is inconsistent with policy. They cannot establish that the event behind the claim occurred, because no artifact establishing that event exists at the moment it occurs.

The result cuts two ways. An honest facility that delivered care absorbs a recoupment because it could not produce a document in the form a reviewer wanted. And a fraudulent operation billing against stolen identities is discovered only after the money is gone, because discovery after payment is the only mode the system currently has.

The specific gap. Nothing attests to the disbursement instruction. It is the point at which a payment becomes irrecoverable in practice, and no party signs a binding of the amount, the payee identity and the evidence that authorized it.
How It Works

Evidence created as care happens, not reconstructed under audit.

One signed record at each consequential event in an episode. No change to clinical workflow. No medical record ever leaves the facility.

1

Discharge

The hospital discharge opens the episode and starts the chain. Captured from message streams that already flow, with no vendor negotiation required.

2

Identity and consent

Beneficiary and provider bound to authoritative identifiers rather than to a local record number, at the moment the relationship is established.

3

Certification

The certifying clinician's eligibility is confirmed at the instant the order is signed, and that determination is frozen into the record.

4

Plan of care

A cryptographic fingerprint of the document. The document itself never moves and is never held by us.

5

Services delivered

One record per visit, bound to the clinician who performed it, created when the visit is documented.

The chain

Each record carries the fingerprint of the one before it and is anchored in an append only log. Alteration, insertion, deletion and reordering are all detectable afterward by a party who trusts nobody involved.

Where It Attaches

Four seams in the existing claims flow.

The orchestration layer attaches at four defined points. It attests. It does not move money.

Claim intake→ Adjudication→ Payment instruction→ Treasury ACH and EFT→ Remittance Unchanged. We are never in this path.
SEAM 1   ANNOTATE
The arriving claim is matched to the evidence chain built during the episode and carries a reference to it. Nothing is gated. The claim proceeds exactly as it does today.
SEAM 2   ADVISE
One question answered before the determination is finalized: is the evidence complete and valid, and does it say what the claim says. Returns a verdict, signed.
SEAM 3   ATTEST
Amount, payee identity and evidence root bound together and signed before the disbursement instruction is released. Nothing attests to this today.
SEAM 4   RETURN
The remittance carries a reference to the proof. The provider holds a durable record of why they were paid instead of rebuilding one years later.
A pilot proves that incomplete evidence is flagged, without that flag affecting whether money moves. Every episode is assessed against a cited documentation requirement set, and every gap is recorded, timestamped and reported. What a pilot withholds is consequence, not detection. The flags are real, they are measurable against the audit outcomes that follow, and they are exactly how a pilot is evaluated. Seam three is the only point at which the layer could ever sit in the payment path, and moving it there is a later decision that routes to human review and never to automated denial.
Demonstration

Watch an episode build, and watch a forgery fail.

The same episode, stepped through. Every record below is in the public conformance bundle, and the verdicts are what the published verifier returns when you run it yourself.

A record is created at the moment the event occurs

A patient is discharged. A signed record is produced immediately, carrying only what is needed to prove the event, and nothing more.

event discharge
episode ep_2026_0918_7741
subject pseudonymized beneficiary reference
facility authoritative provider identifier
occurred 2026-09-18T14:22:00Z
evidence fingerprint of discharge summary
signed by the discharging hospital's own key
What is not in it. No chart, no notes, no images, no diagnosis text, no raw beneficiary identifier. A fingerprint proves the document existed and has not changed. It cannot reproduce the document.

Each record is bound to the one before it

Five events across the episode. Each carries the fingerprint of its predecessor, and each is signed by the organization that made the assertion. No party signs on behalf of another.

✓ 1. discharge        signed by hospital
✓ 2. identity, consent  signed by home health agency
✓ 3. certification     signed by certifying practice
✓ 4. plan of care      signed by home health agency
✓ 5. visits delivered   signed by home health agency

chain 5 records, sequence intact, anchored
To construct this episode falsely you would need the signing keys of three separate organizations, and you would need to have had them before the anchor was written.

The claim arrives and is matched to its evidence

At claim intake the submission is matched to the episode and annotated with a reference to its evidence root. This is enrichment. Nothing is gated and the claim proceeds exactly as it does today.

claim home health, 60 day certification period
episode ep_2026_0918_7741
billed 5 visits
chain says 5 visits
annotation reference to evidence root attached

The verdict, before the payment determination is finalized

The verification service walks the chain, checks every signature, confirms each record is in the anchored log, and answers one question. It returns a verdict and signs the verdict itself, so the answer is as checkable as the evidence underneath it.

✓   COMPLETE  ·  evidence chain valid and consistent with the claim
Verification is a local operation. No cross system joins, no synchronous call outside the boundary. Target under fifty milliseconds at the verification seam. That target has not been measured at federal volume and we do not quote it as a result.

Now alter one field

Someone changes the discharge disposition code in record one, two years later, to support a claim that would otherwise fail. This is the single most common form of documentation fraud, and today it is close to undetectable.

✗ 1. discharge        signature does not verify
✗ 2. identity, consent  predecessor fingerprint mismatch
✓ 3. certification
✓ 4. plan of care
✓ 5. visits delivered

failing record index 1, discharge
✗   UNVERIFIABLE  ·  record 1 altered after signing
Re-signing the altered record does not help. Its fingerprint no longer matches what record two carries, and it no longer reconciles to the anchored log. The failure names the record, the position and the reason.

The phantom claim

A claim arrives from an entity billing against a stolen identity. There is no episode underneath it. No discharge, no admission, no order, no visits. This is the pattern behind more than a million stolen Medicare identities in a single federal enforcement action.

claim submitted, well formed, rule compliant
episode no matching evidence chain
records 0
⚠   INCOMPLETE  ·  no evidence chain exists for this claim
This is the finding, not an accusation. It routes to human review. What changes is the economics of the fraud: billing becomes cheap only when nobody can check the story behind it. Under this design a fraudulent operation would need a live evidence stream from a real facility, signed with that facility's key, anchored before the claim is submitted.

The walkthrough above is illustrative. The live demonstration runs on a working reference implementation, offline, on a machine we hand to you, and includes independent verification on a second machine that has never contacted our systems.

Boundaries

What it never does, and why that is the architecture.

Each of these is a structural property rather than a policy commitment. A policy can be waived when a schedule slips. A missing capability cannot.

Never adjudicatesCoverage, medical necessity and pricing determinations stay exactly where they are today.
Never moves moneyMedicare pays providers by Treasury ACH and EFT. We are not in that path and do not want to be.
Never holds a medical recordFingerprints, minimal signed assertions and pointers. No charts, notes, images or free text.
Never blocks a paymentFails open, absolutely. If the service is unavailable, claims flow exactly as they do today.
Never replaces a systemIt annotates existing systems. Nothing gets ripped out and nothing is migrated.
Never requires workflow changeCapture works from message streams and standard hooks that clinical systems already implement.

Nothing in it worth stealing

The largest healthcare breach on record reached an estimated 192.7 million people because the system was holding data it needed to move. A complete compromise of this layer would disclose episode structure and pseudonymous references. No clinical content, because none is present. Beneficiary identifiers appear only as keyed pseudonyms, with the key held separately from the records.

It deploys inside your boundary

The layer runs on the operator's own infrastructure, under the security authorization that already exists there. We do not host a service and do not take custody of federal, clinical or payment data at any point. The record format is a published specification and the verifier runs standalone and offline, so every proof produced remains verifiable without us.

Precedent

This pattern is not new. It is new to healthcare payment.

Under Executive Order 14028 and OMB Memorandum M-22-18, federal agencies may use software only from producers who attest to secure development practices. The supporting ecosystem is cryptographic attestation backed by an append only transparency log with inclusion proofs. The same construction has operated at internet scale in Certificate Transparency for over a decade.

The government already accepts, requires and operates this model to answer whether a piece of software is what it claims to be. We apply the same evidence pattern to answer whether a healthcare event was what it claims to be.

That makes this an extension of an accepted control into a new domain, rather than a novel proposal. The same construction underlies Certificate Transparency, which every browser relies on to detect a mis-issued certificate. A federal program and a commercial health plan are asking the same question of their evidence, and the answer does not change with the buyer.

Published standards, not proprietary

Post-quantum signatures under the current NIST standard. Transparency log construction per the specification behind Certificate Transparency. Canonical serialization per published RFC. Clinical capture on HL7, FHIR and CDS Hooks.

You are not buying a hostage

The record format is a published specification. The verifier runs standalone and offline. A second implementation can be built by a third party from the specification alone, and every proof we produce stays verifiable without us.

Crypto agility by design

Algorithm and version are recorded inside every signed payload, and all cryptography passes through a single provider interface. A federal build selects a validated module and swaps it in. A commercial deployment makes the same choice on its own terms. That is a deployment decision, not a rewrite.

Implementation Status

Proven today, and the path on everything else.

Stated plainly, because a reviewer who finds the gaps themselves discounts everything above them. This is the same inventory we hand to engineering and security teams before they ask, and it is why what sits above it can be relied on.

Proven, running, reproducible

  • Working reference implementation with the record format frozen and specified independently of the code
  • Post-quantum signatures under the current NIST standard, behind a single swappable provider interface
  • Append only log with inclusion proofs, verified across 2,080 checks with zero failures and forged proofs rejected in every case
  • Identical output across two independent machines, which is the property cross organizational verification depends on
  • Clinical message capture demonstrated on a real message standard, with negative tests that reject malformed input rather than tolerating it
  • Four tamper cases demonstrated: alteration, reordering, deletion, and verification after key rotation
  • Beneficiary pseudonymization, so a raw identifier never enters a record

Deployment Requirements and Items to Be Validated

MedXT’s core evidence-verification technology is operational today. Moving from the current implementation into customer production environments introduces additional integration, security, compliance and performance requirements that will vary by deployment.

  • Customer and federal integration. Production deployments will be configured for the systems, workflows, data environments and security requirements of each customer
  • Security and authorization. Applicable security controls, validated cryptographic components, certifications and authorization requirements will be addressed based on the specific deployment environment
  • Production-scale validation. Performance, scalability and operational resilience will be evaluated under representative production workloads as deployments progress
  • Real-world impact measurement. Pilot and production deployments will provide the operating data needed to measure effectiveness, including the technology’s potential impact on improper payments, fraud, errors and other preventable losses
  • Deployment-specific compliance. Regulatory, privacy, data-access and governance requirements will be addressed according to the customer, use case and operating environment
What a complete, valid chain establishes, and what it does not. It establishes that a record is authentic, unaltered, attributable to a verified actor and correctly sequenced. It does not establish that the underlying clinical event occurred. An actor holding valid credentials can sign an attestation about a service never rendered. No cryptographic construction closes that, and anyone claiming otherwise should be treated with suspicion. What changes is that the false statement becomes attributable, contemporaneous and permanent.
Who This Is For

Programs where payment accuracy is a stated objective.

Federal health programs

Fee-for-service payment integrity, where the dominant failure is evidentiary rather than criminal and post-payment recovery is structurally limited.

Claims processors and primes

Organizations modernizing claims infrastructure, where verification interfaces can be designed in rather than retrofitted to production systems later.

Health plans

Medicare Advantage risk adjustment, where the plan carries the overpayment itself, findings extrapolate across the contract, and the threshold question in an audit is whether an authenticated encounter record exists, by an eligible provider, in the service year. Also verified inputs to existing analytics and claim intelligence, which raises the ceiling on what those capabilities can conclude.

Providers

Post-acute organizations carrying a disproportionate documentation and audit burden, who would hold the evidence record rather than reconstruct one on demand.

See it run, then verify it yourself.

The walkthrough is a working demonstration, not slides. We build the open source verifier from source, verify a synthetic episode, then break it in front of you: alter one field and watch the check fail, and rewrite the log as its own operator and watch a witness refuse to co-sign it. We run the failures ourselves because a demonstration that only succeeds proves nothing. Then your engineer takes the keyboard and does the same on their own machine.

Request a technical walkthrough