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US healthcare is a three-way relationship between patients, the providers who treat them and the payers who fund that care: commercial insurers, employers and government programs such as Medicare and Medicaid. Most of its complexity, and most of the software, lives in the paperwork between providers and payers: checking coverage, getting approval, coding what happened, submitting a claim and reconciling the payment, all under HIPAA’s privacy rules.

This learning path follows that work from the basics to the systems engineers build. It started from the HealthTech Decoded YouTube channel, and each post links the videos that cover its topic.

The workflow in one picture

flowchart TB
    subgraph before["Before the visit"]
        direction LR
        A["Enrollment<br/>834 · 820"] --> B["Eligibility check<br/>270 / 271"] --> C["Prior authorization<br/>278"]
    end
    subgraph claim["The visit and the claim"]
        direction LR
        D["Care delivered and coded<br/>ICD-10 · CPT · HCPCS"] --> E["Claim submitted<br/>837P / I / D"] --> F["Acknowledgment and status<br/>999 · 277CA · 276/277"]
    end
    subgraph pay["Getting paid"]
        direction LR
        G["Repricing and<br/>adjudication"] --> H["Payment and remittance<br/>835"] --> I["Patient bill<br/>deductible · copay · coinsurance"]
    end
    before --> claim --> pay

The numbers are ANSI X12 transaction sets, the electronic formats HIPAA mandates for each step. HIPAA’s privacy and security rules apply to every step.

Learning path

Level 1 · Foundations

Who the players are, how insurance plans work and what patients pay. Start here if US healthcare is new to you.

The US healthcare ecosystem

1. The US Healthcare Ecosystem: Who's Who Patients, providers, payers, employers, clearinghouses, PBMs and regulators: the players in US healthcare and what each one does.
2. How Money Flows in US Healthcare Coming soon Follow a dollar from the premium a member pays to the payment a provider receives, and see where fee-for-service and value-based payments differ.
3. Healthcare Identifiers: NPI, TIN, Taxonomy, Payer ID and Member ID Coming soon The IDs that appear on every claim and eligibility check, who issues them and how systems use them to match people and organisations.

Health insurance and plan types

4. Health Plan Types: HMO vs PPO vs EPO vs POS vs HDHP How each plan type trades off cost, choice of provider and referral rules, with examples of which one fits which patient.
5. In-Network vs Out-of-Network Providers What a provider network is, how payers contract with providers, and why the same visit can cost very different amounts depending on network status.
6. Patient Cost Sharing: Premium, Deductible, Copay, Coinsurance and Out-of-Pocket Max Why insured patients still get bills: a worked example of how a claim's allowed amount is split between the plan and the patient.
7. Employer Coverage, ERISA and the ACA Marketplace Coming soon Where most Americans get insurance: employer-sponsored plans, fully insured vs self-funded (ERISA) plans, and individual coverage on the ACA marketplace.

Government programs

8. Medicare Explained: Parts A, B, C and D The federal program for people 65 and over and some people with disabilities: what each part covers, what it costs and how enrollment works.
9. Medicaid and CHIP Explained The joint federal-state programs for people on low incomes and for children: eligibility, managed care organisations, and why every state's program differs.
10. Medicare vs Medicaid, and Dual-Eligible Members A side-by-side comparison of the two programs, and how coverage and claims work for people who qualify for both.
11. The 2027 Medicaid Changes Under the One Big Beautiful Bill Act What the 2025 law changes for Medicaid: work requirements, six-month eligibility checks, shorter retroactive coverage and new copays, and when each takes effect.

Level 2 · Core workflows

The business processes that turn a visit into a payment, and the rules that govern patient data.

Revenue cycle, coding and claims

12. Revenue Cycle Management (RCM) End to End Coming soon The provider-side process from scheduling to final payment: front-end, mid-cycle and back-end steps, and the KPIs that measure them.
13. Patient Registration and Eligibility & Benefits Verification Coming soon How a clinic confirms a patient's coverage before the visit, what a benefits response tells it, and what breaks when this step is skipped.
14. Medical Coding Basics: ICD-10-CM, CPT and HCPCS The three code sets on every claim (diagnoses, procedures and supplies), plus modifiers and how codes link together.
15. CPT vs HCPCS: Real Examples to Tell Them Apart A practical guide with lab, office-visit and durable medical equipment examples, and why Medicare and commercial payers treat the code sets differently.
16. The Claim Lifecycle: From Submission to Adjudication Coming soon What happens to a claim after the provider sends it: clearinghouse edits, payer acceptance, adjudication rules and the final decision.
17. Claim Repricing: How a $5,000 Bill Becomes $900 How payers and repricers apply contracted rates, fee schedules and DRGs to billed charges, and what that means for providers and patients.
18. Remittance, EOB vs ERA and Payment Posting Coming soon How payment comes back: the member's Explanation of Benefits, the provider's 835 ERA, adjustment reason codes, and how payments get posted.
19. Claim Denials and Appeals Coming soon Why claims get denied, the most common denial reasons, and how providers prevent, work and appeal them.
20. Coordination of Benefits: When a Patient Has Two Plans Coming soon How payers decide which plan pays first, the birthday rule, Medicare Secondary Payer rules, and how COB data travels on a claim.

Utilization management and prior authorization

21. Utilization Management Explained How payers review whether care is medically necessary (prospective, concurrent and retrospective review) and why it leads to denials.
22. Prior Authorization: The Step-by-Step Workflow When pre-approval is required, how a request moves between provider and payer, and why delays and denials happen.

HIPAA, privacy and regulation

23. HIPAA Explained: Covered Entities, Business Associates and the Rules What HIPAA requires, who it applies to, and its Privacy, Security, Breach Notification, Enforcement and Transactions rules, plus the Omnibus update.
24. PHI, the 18 Identifiers and the Minimum Necessary Standard Coming soon What counts as protected health information, the 18 HIPAA identifiers, and how 'minimum necessary' shapes system and API design.
25. No Surprises Act and Price Transparency Coming soon The federal rules against surprise out-of-network bills, the independent dispute resolution process, and the hospital and payer price-transparency files.

Level 3 · Health data exchange

The standards that carry those workflows between systems, from EDI X12 to HL7, FHIR and DICOM.

Healthcare EDI (ANSI X12)

26. Introduction to Healthcare EDI and ANSI X12 What EDI is, why HIPAA mandates X12 5010, and how an X12 file is built from envelopes, loops, segments and elements.
27. The X12 Transaction Map: 834 to 835 and Everything in Between Which transaction set is exchanged at each step of the healthcare workflow, who sends it and who receives it.
28. X12 834 and 820: Enrollment and Premium Payments Coming soon How employers and exchanges send member enrollments to payers (834) and pay premiums (820), with the key loops and maintenance codes.
29. X12 270/271: Eligibility and Benefits Inquiry Coming soon The request a provider sends to check coverage and the payer's response, segment by segment, in real-time and batch modes.
30. X12 278: Prior Authorization Request and Response How the 278 carries a prior authorization request to the payer and the decision back, with the key loops, segments and real examples.
31. X12 837 Part 1: Submitter, Receiver, Provider, Subscriber and Patient Loops Chapter 1 of the 837 deep dive: loops 1000A to 2000C, the hierarchy that ties a claim to its billing provider, subscriber and patient across 837P, 837I and 837D.
32. X12 837 Part 2: The Claim Information Loop (2300) Chapter 2: the CLM segment, dates, prior-auth references, diagnosis codes, amounts, providers and coordination of benefits in loop 2300.
33. X12 837 Part 3: Service Lines (Loop 2400) Chapter 3: LX and SV1/SV2/SV3 service lines, modifiers and diagnosis pointers, line dates, line-level providers, pricing and adjudication (SVD/CAS).
34. X12 835: Claim Payment and Remittance Advice Coming soon How a payer tells a provider what it paid and why: BPR/TRN payment details, CLP claims, SVC lines and CAS adjustments.
35. X12 276/277, 277CA and 999: Claim Status and Acknowledgments Coming soon How senders learn whether a file was accepted, which claims were rejected and where a claim stands in adjudication.

Clinical interoperability (HL7, FHIR, DICOM)

36. EHR, Practice Management and Payer Core Systems Coming soon What EHRs, practice management and payer core administration systems do, how the major vendors fit in, and where integrations happen.
37. HL7 v2 Messages: ADT, ORM, ORU and SIU Coming soon The pipe-delimited messages hospitals still use to move admissions, orders and results between systems, and how interface engines route them.
38. FHIR Fundamentals: Resources, REST APIs and SMART on FHIR Coming soon The modern standard for health data APIs: resources, references, profiles and US Core, plus SMART on FHIR for authorisation.
39. CMS Interoperability and Prior Authorization Rule: Payer FHIR APIs Coming soon The CMS rules requiring payers to expose Patient Access, Provider Access, Payer-to-Payer and Prior Authorization APIs, and the Da Vinci guides behind them.
40. Medical Imaging Systems: DICOM, PACS and RIS Coming soon How imaging orders, studies and reports move between radiology systems, the DICOM standard, and imaging in the cloud.

Level 4 · Health tech engineering & strategy

Building compliant systems on these standards, and the payment models changing the industry.

Health tech engineering

41. De-identifying PHI in X12 Files with Python (pyx12) A hands-on walkthrough of Safe Harbor and Expert Determination, then a Python framework that de-identifies and re-identifies PHI in 837 and 835 files.
42. Parsing and Validating X12 Files in Code Coming soon Tools and patterns for reading, generating and validating X12 transactions: open-source parsers, SNIP validation levels and test data.
43. Building a HIPAA-Compliant Architecture on AWS, Azure and GCP Coming soon What a BAA covers, which services are HIPAA-eligible, and the encryption, access, logging and network controls a PHI workload needs in the cloud.
44. Healthcare Data Services in the Cloud: AWS, Azure and Google Cloud Coming soon Managed FHIR, DICOM and HL7 v2 stores on the three major clouds: AWS HealthLake, Azure Health Data Services and the Google Cloud Healthcare API.
45. AI in US Healthcare: Prior Auth, Coding and Claims Automation Coming soon Where AI and LLMs are being used across payer and provider workflows, and the HIPAA, bias and explainability guardrails they need.

Value-based care and analytics

46. Value-Based Care, ACOs and Alternative Payment Models Coming soon The shift from paying for volume to paying for outcomes: shared savings, capitation, bundled payments and accountable care organisations.
47. Risk Adjustment and HCC Coding Coming soon How Medicare Advantage and ACA plans are paid based on members' health status, how HCC models work, and why documentation matters.
48. Quality Measures: HEDIS, Star Ratings and MIPS Coming soon How payers and providers are scored on quality, where the data comes from, and how scores affect payment.
49. Healthcare Claims Data and Analytics Coming soon Building a claims data platform: data models, member and provider matching, cost and utilisation metrics, and fraud, waste and abuse detection.