How CMS made 18 million lines of legacy code readable with 8090
As part of the ClaimsCore modernization, 8090 is extracting 100,000+ business rules from Medicare’s claims systems: every rule written in plain English, traced to the exact lines of code it came from, and matched across every system it touches.
Client
Sector
Federal · Medicare
Program
ClaimsCore modernization
Engagement
Legacy business rule extraction
Approach
Static analysis pipeline
0M+
lines of Assembly and COBOL, read and analyzed line by line.
0+
discrete business rules to identify, document, and trace.
0+ yrs
of policy logic, much of it written by authors who have since retired.
Specification
A record that did not exist before.
A plain-English specification for rules that had lived only inside the code.
Traceability
Every statement sourced.
Every rule tied to the exact source lines and change history it came from.
Cross-system
One thread through four systems.
Each rule matched across CWF, DME, FISS, and MCS into a single connected view a person can actually follow, a view that never existed before.
50+ years of policy logic, sparsely documented.
The logic that decides how Medicare claims are validated and paid in its most complete form lives inside the code that runs the systems. The manuals and Change Requests describe the policy, but no document captures how decades of accumulated interpretations and edge cases actually behave in the running systems. The engineers who wrote and layered that logic over the years are retiring, and each departure takes part of the picture with it.
This is institutional knowledge at the scale of a national program, walking out the door one retirement at a time.
A pipeline that reads the code and documents every rule.
01
Read
8090 built a pipeline that standardizes the different styles of Assembly and COBOL in the code and reads all of it through static analysis, examining what the code does without running it. This work is analysis, not search and copy.
02
Separate
It follows the logic across thousands of interconnected programs and separates each business rule from the technical plumbing around it.
03
Document
Every rule is drafted in plain English, written to be read by the people who own Medicare policy, including reviewers who have never worked in COBOL.
Every rule traces back to its source.
A documented rule is only useful if a reviewer can trust it. Every rule is written as a structured Given/When/Then scenario: plain English a policy owner can read, precise enough to carry the exact logic of the code. Every line shows where it came from: traced to the lines of code behind it, or confirmed in CMS documentation. If a statement cannot be sourced, it does not go in the record.
Interactive · Swipe to select a rule to follow it to the source
Review app · Spec-to-source
Traced142 rules · CLM0420
BR-2231 · Timely filing limit
Timely filing limit
Illustrative. Rules and code shown are representative, not extracted CMS source.
A single thread of policy, stitched across four independent systems.
Medicare claims run through separate systems (CWF, DME, FISS, and MCS), each built and maintained independently for decades, each with its own version of the same policy written into it. 8090 reverse-engineers all four and matches each rule across them into a single view a person can actually follow: one policy, every version, connected.
No manual and no traditional engineering effort has ever produced that view. It exists now because the pipeline reads every system the same way and ties the pieces together.
One rule, correlated across every system
FISS · Part A Institutional
Filing check at claim intake
Applies the limit when the institutional claim is received.
MCS · Part B Professional
Same limit, its own edit
The same 12-month policy, implemented separately with its own reason codes.
DME · Durable Medical Equipment
Supplier exceptions
Evaluates supplier exception codes against the same limit.
CWF · Common Working File
Cross-system check
Checks every claim decision against the beneficiary’s history.
Timely filing limit
One policy · four independent implementations, correlated into a single rule.
A review application and one searchable reference.
Along with the rule catalog, 8090 built the tools CMS reviewers use to work with it: a way to review each rule against its source, and one place to look everything up.
A browsable review application
Filtering, side-by-side views of each rule against its source code, and tools built for the experts doing the review.
One searchable reference
Scattered program documentation consolidated into a single, searchable record of how the rules actually work.
Documentation kept in step
Where the running code and official documentation have drifted apart, the record notes the difference so CMS can review and reconcile it over time.
A verified baseline for the modernization.
CMS is modernizing its Medicare claims systems under the ClaimsCore initiative. The rules 8090 documents become part of the baseline the teams building the replacement use to configure, test, and validate their work.
For the first time there is a plain-language, verified record of how Medicare claims processing actually works: a foundation for the next generation of systems rather than knowledge locked inside aging code. CMS keeps the policy and the judgment. The technology does the reading and the first draft.
* 8090 is one of several contractors supporting CMS's business rules extraction work for the ClaimsCore program. Nothing on this page states or implies that CMS endorses, partners with, or recommends 8090, or that 8090 is the only contractor on the work.
Are old systems holding your business back?
8090 reads the code behind your most critical systems and turns it into a plain-language, traceable record your team can review and trust as you modernize.