Guides
Healthcare data, explained plainly
No fluff, no fabricated numbers — real guidance on NPI numbers, the NPPES registry, ICD-10-CM codes and validation, written for billers, coders and the developers building on healthcare data.
HCC Coding Explained: How Hierarchical Condition Categories Work
What HCC coding is, how RAF scores get calculated, and what changed under CMS-HCC V28. Look up any ICD-10-CM code free.
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ICD-10 Code for Prostate Cancer (C61) Explained
C61 is the ICD-10-CM code for malignant neoplasm of prostate. How it's billed, how metastatic prostate cancer ICD-10 coding works, and how it differs from bladder cancer codes.
How to Apply for an NPI Number (Step by Step)
A plain walkthrough of how to apply for an NPI number online through NPPES — the I&A account, Type 1 vs Type 2, taxonomy, and the common mistakes that slow enumeration down. It's free.
ICD-10 Code for Osteoporosis (M80–M81 Explained)
The osteoporosis ICD-10 code isn't one code — M80 covers fracture, M81 covers no fracture, and osteopenia is a separate M85.8- diagnosis.
ICD-10 Code for Congestive Heart Failure (I50)
The ICD-10 code for congestive heart failure sits under I50, but I50 alone isn't billable. Here's how HFrEF, HFpEF and CHF codes actually break down.
What Is Medical Coding? A Complete Beginner's Guide
Medical coding turns clinical care into standardised diagnosis and procedure codes for billing and public health. Here's how it actually works.
HCPCS Level II Codes Explained (vs CPT)
HCPCS covers everything CPT doesn't — durable medical equipment, ambulance rides, prosthetics, certain injectable drugs. Here's how the format works and how to run a reliable HCPCS code lookup.
NPI vs DEA Number vs CAQH ID: What's the Difference?
NPI, DEA number, CAQH ID, and PTAN look similar but aren't. Here's who issues each one, what it's for, and why you can't look up a DEA number from an NPI.
ICD-10 vs ICD-9: How to Read a GEM Crosswalk
Why the US retired ICD-9 codes for ICD-10-CM and ICD-10-PCS in 2015, how the two current systems differ, and how to read a GEM crosswalk when old and new data need to meet.
Provider Taxonomy Codes: The Complete NUCC Guide
What a provider taxonomy code is, how the three-level NUCC hierarchy works, why one NPI can carry several codes, and how to look one up by hand or by API.
What is an NPI number? A plain-English guide
An NPI is the 10-digit National Provider Identifier every US healthcare provider uses on claims. Here's what it is, who needs one, how to read it, and how to look one up.
How ICD-10-CM codes work (and how to read one)
ICD-10-CM is the US diagnosis code set — about 74,000 billable codes. Here's how a code is structured, what 'billable' means, and how the chapters and hierarchy fit together.
The healthcare reference data your AI agent actually needs
An AI agent that touches billing, credentialing, or claims needs three things it cannot reliably generate on its own: authoritative NPI resolution, ICD-10 validation, and taxonomy lookup. Here's why, and how to wire it in.
How to validate an NPI number (the check-digit algorithm)
Every valid NPI has a built-in check digit computed with the Luhn algorithm over a fixed 80840 prefix. Here's exactly how it works, a worked example, and how to validate NPIs in bulk.
NPI taxonomy codes (NUCC) explained
Every NPI carries one or more taxonomy codes that describe the provider's specialty. Here's what NUCC taxonomy codes are, how they're structured, and how to read one like 207Q00000X.
What does "billable" mean for an ICD-10 code?
Not every ICD-10-CM code can go on a claim. "Billable" means the code is a leaf — the most specific level the classification supports. Here's how to tell the difference and why headers get rejected.
ICD-10 vs CPT vs HCPCS: what's the difference?
Three code sets show up on almost every medical claim, and they answer three different questions: why (ICD-10), what was done (CPT), and what supplies or services were used (HCPCS). Here's how they differ and who maintains each.
ICD-10 code for type 2 diabetes (E11)
Type 2 diabetes lives under E11 in ICD-10-CM — but E11 itself isn't billable. Here's the E11 family, when to use E11.9 vs a complication code, and how to code to the specificity a claim needs.
What is the NPI Registry (NPPES)?
NPPES is the CMS system that issues and publishes every US provider's NPI. Here's what it actually contains, who maintains it, how current it is, and how to search it — by browser or by API.
How to find a provider's NPI number
Need a physician, clinic, or organization's NPI for a claim, credentialing file, or EHR record? Here's how to search by name, organization, and state — and what to do when you get duplicate matches.