Why big replacements struggle
Integrated eligibility, child support and child welfare systems carry decades of policy in their code. Replacing one in a single project means rebuilding every rule, migrating every record and retraining every worker at once. These projects often run long, and the agency carries two systems while it waits.
An incremental approach replaces the system a function at a time. Each step is small enough to test fully and roll back if needed, and the agency sees value long before the last legacy screen is turned off.
Put tests around what exists
Before changing anything, build an automated regression suite that captures how the current system behaves. Start with the transactions that matter most: applications, eligibility determinations, notices and payments. These tests become the safety net for every later change and usually pay for themselves within a few release cycles by replacing manual regression testing.
Move one function at a time
Pick a function with clear boundaries, such as notice generation or document upload, and build it as a modern service. Route that function to the new service while the rest of the legacy system keeps running. Repeat. This pattern, often called the strangler approach, keeps the risk of each step small and visible.
Treat data migration as its own workstream
Data is where incremental projects most often slip. Plan migration early, profile the legacy data, agree on rules for records that do not fit the new model, and run trial migrations long before cutover. Reconcile counts and totals after each run so problems surface early.
Low-code platforms and rules
Many agencies modernize onto case management platforms such as Pega or Salesforce. These platforms speed delivery, but they work best when policy rules are documented in plain language first and reviewed with program staff. A rule that is unclear on paper will be wrong in configuration.
A checklist for the first release
- Regression suite covering the top transactions, running in the pipeline
- One function selected with clear inputs and outputs
- Routing in place so the function can switch between old and new
- Data profile of the records the function touches
- Rollback plan tested before go-live
- Measures agreed with the program: processing time, error rate, worker feedback
Meritore's Application Development and Health & Human Services practices support agencies through incremental modernization. Learn more.
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