VB6 Insurance Underwriting Systems: Extracting Business Logic from 25-Year-Old Forms

The most dangerous code in your enterprise isn't the new microservice your juniors just pushed to production—it’s the Visual Basic 6.0 (VB6) underwriting form that has been calculating premiums since 1998. In the insurance sector, these "black boxes" manage billions in risk, yet the developers who wrote them have long since retired. When you face the task of insurance underwriting systems extracting core logic, you aren't just looking at a UI migration; you are performing digital archeology on $3.6 trillion of global technical debt.

The challenge is that VB6 doesn't separate concerns. Business logic is inextricably tangled with UI events like

and . Attempting a manual rewrite often results in the "Paralysis of Analysis," where teams spend months documenting a system only to find the documentation is obsolete before the first line of React is written.

TL;DR: Manual migration of VB6 underwriting systems takes an average of 40 hours per screen and has a 70% failure rate. Replay utilizes Visual Reverse Engineering to record user workflows and automatically generate documented React components and design systems. This reduces the modernization timeline from years to weeks, achieving a 70% time saving by focusing on observed behavior rather than deciphering "spaghetti" legacy source code.

The Hidden Complexity of Insurance Underwriting Systems Extracting Logic#

Insurance underwriting is a game of edge cases. A 25-year-old system likely contains thousands of hidden validation rules: state-specific compliance checks, occupational hazard multipliers, and complex actuarial tables. According to Replay's analysis, 67% of legacy systems lack any form of up-to-date documentation, leaving modern architects to guess at the original intent of the code.

When we talk about insurance underwriting systems extracting business rules, we are dealing with three distinct layers of debt:

1. •The UI Layer: Non-standard controls (like old MSFlexGrids) that don't map directly to modern web components.
2. •The State Layer: Global variables and hidden form fields that track the "health" of an application during a session.
3. •The Logic Layer: Procedural code blocks that calculate risk without a centralized API.

Visual Reverse Engineering is the process of capturing the runtime behavior of a legacy application through video recordings and interaction logs, then using AI to reconstruct that behavior into modern, documented code structures.

Instead of reading 50,000 lines of

and files, Replay looks at the output. By recording an underwriter processing a policy, Replay identifies the data flow, the validation triggers, and the component hierarchy.

Why Manual Rewrites of Underwriting Forms Fail#

Industry experts recommend moving away from the "Big Bang" rewrite model. The statistics are grim: 70% of legacy rewrites fail or significantly exceed their timelines. For a typical enterprise, an 18-month average enterprise rewrite timeline is the best-case scenario. For complex insurance platforms, this can stretch to three years, by which time the market requirements have shifted again.

The manual approach involves a developer sitting with an underwriter, taking notes, and then trying to find the corresponding logic in the VB6 IDE. This is prone to "The Telephone Game" effect—nuance is lost at every step.

The Technical Debt of VB6 Event-Driven Logic#

In VB6, logic is often "trapped" in the UI. Consider a simplified premium calculation. In the legacy system, it might look like this:

vb
' Legacy VB6 Snippet - Trapped Logic
Private Sub txtAge_Change()
    If Val(txtAge.Text) > 65 Then
        lblRiskWarning.Caption = "High Risk Category"
        curPremium = curBase * 1.5
    Else
        lblRiskWarning.Caption = ""
        curPremium = curBase
    End If
    UpdateTotalDisplay
End Sub

To a modern developer, this is a nightmare. The logic is tied to a text change event. If you want to use this logic in a web portal or a mobile app, you have to find it, extract it, and rewrite it. When insurance underwriting systems extracting logic occurs manually, developers often miss the "side effects"—like the

call which might trigger another ten hidden calculations.

Replay's Flows feature maps these interactions. By recording the user entering "70" into the age field, Replay identifies that the "High Risk Category" label appeared and the premium value changed. It then blueprints the underlying state machine.

Modernizing to React and TypeScript with Replay#

The goal of any modernization project should be a clean, maintainable Design System. Replay doesn't just give you a "blob" of code; it generates a structured Component Library.

Here is what the extracted logic looks like when converted into a modern React component using Replay’s AI Automation Suite:

typescript
// Modern React Component generated via Replay Blueprints
import React, { useState, useEffect } from 'react';
import { TextField, Alert, Typography } from '@your-org/design-system';

interface UnderwritingProps {
  basePremium: number;
  onPremiumChange: (newPremium: number) => void;
}

export const AgeValidationModule: React.FC<UnderwritingProps> = ({ 
  basePremium, 
  onPremiumChange 
}) => {
  const [age, setAge] = useState<number | string>('');
  const [isHighRisk, setIsHighRisk] = useState(false);

  useEffect(() => {
    const numericAge = Number(age);
    if (numericAge > 65) {
      setIsHighRisk(true);
      onPremiumChange(basePremium * 1.5);
    } else {
      setIsHighRisk(false);
      onPremiumChange(basePremium);
    }
  }, [age, basePremium, onPremiumChange]);

  return (
    <div className="p-4 border rounded-lg shadow-sm">
      <TextField
        label="Applicant Age"
        value={age}
        onChange={(e) => setAge(e.target.value)}
        type="number"
      />
      {isHighRisk && (
        <Alert severity="warning" className="mt-2">
          <Typography variant="body2">High Risk Category Identified</Typography>
        </Alert>
      )}
    </div>
  );
};

This React component is modular, typed, and ready for a modern CI/CD pipeline. By using Replay, the transition from the VB6

to this functional component happens in hours, not days.

Strategic Steps for Insurance Underwriting Systems Extracting Data#

To successfully navigate a legacy migration, enterprise architects must follow a structured framework. Industry experts recommend the "Record, Refine, Replicate" methodology.

1. Recording the Gold Standard#

The first step is capturing the "Gold Standard" of your underwriting process. This involves having your most experienced underwriters perform standard and complex tasks while Replay records the session. This creates a visual and data-driven source of truth. Unlike static code analysis, this captures how the system is actually used, ignoring dead code that hasn't been executed in a decade.

2. Building the Component Library#

Once the workflows are captured, Replay’s Library feature identifies recurring UI patterns. In insurance systems, this often includes complex data grids, multi-step wizards, and specialized input masks for policy numbers. Replay aggregates these into a unified Design System, ensuring that the new React application looks and feels consistent.

3. Logic Extraction and Blueprinting#

The core of insurance underwriting systems extracting success lies in the Blueprints editor. Here, architects can review the AI-generated logic. If the legacy system had a specific quirk—perhaps a rounding error that must be maintained for regulatory consistency—it can be flagged and preserved in the new TypeScript code.

typescript
/**
 * REPLAY BLUEPRINT: Premium Calculation Logic
 * Extracted from: frmUnderwriting.frm (Line 452)
 * Note: Maintaining the "Floor" rounding method used in the 1998 system 
 * to ensure regulatory premium parity.
 */
export const calculateAdjustedPremium = (base: number, multiplier: number): number => {
  // Legacy systems often used specific rounding logic that must be replicated
  // to avoid "premium drift" during migration.
  return Math.floor(base * multiplier * 100) / 100;
};

Security and Compliance in Regulated Environments#

For Financial Services and Healthcare, security isn't an afterthought. Moving legacy data and logic into a modern cloud environment requires rigorous compliance. Replay is built for these environments, offering SOC2 and HIPAA-ready configurations, as well as On-Premise deployment options for organizations with strict data residency requirements.

When insurance underwriting systems extracting logic is performed, Replay ensures that PII (Personally Identifiable Information) can be masked during the recording phase. This allows developers to work with the structure and logic of the system without ever seeing sensitive policyholder data.

The Cost of Inaction: The $3.6 Trillion Problem#

Every day a legacy VB6 system remains in production, the risk increases. The "bus factor" for these systems is often dangerously low—sometimes a single individual holds the key to the entire underwriting engine.

According to Replay's analysis, the cost of maintaining a legacy system is 3x higher than the cost of running a modern cloud-native equivalent. This includes:

• •Infrastructure Costs: Maintaining old Windows Servers or terminal services.
• •Opportunity Costs: Inability to integrate with modern AI/ML risk assessment tools.
• •Talent Costs: Paying a premium for "legacy specialists" or spending months training new hires on dead languages.

By utilizing Visual Reverse Engineering, organizations can bypass the traditional "rewrite" risks. You aren't guessing what the code does; you are observing it, documenting it, and transforming it.

Case Study: Modernizing a 20-Year-Old Policy Suite#

A Tier-1 insurance provider recently faced the challenge of insurance underwriting systems extracting rules from a massive VB6 desktop application. They had over 400 unique screens and 1.2 million lines of code.

The Manual Estimate: 3 years, $12 million, and a high risk of failure. The Replay Solution:

1. •Recorded 50 core underwriting "Flows."
2. •Generated a React Design System in 2 weeks.
3. •Automated the conversion of 80% of the forms.
4. •Result: The project was completed in 6 months at 30% of the projected cost.

The key was focusing on the "Live Logic." By ignoring the 40% of the codebase that was redundant or unreachable, the team accelerated the migration and delivered a superior user experience for their underwriters.

Frequently Asked Questions#

How does Replay handle custom VB6 controls that don't have a modern equivalent?#

Replay’s AI Automation Suite analyzes the behavior and data structure of custom controls (like third-party ActiveX components). It then maps these to the most appropriate modern React component from your library or creates a functional equivalent that maintains the same data contract. This ensures that even "exotic" legacy UI elements are modernized without losing functionality.

Is it possible to extract logic without having the original VB6 source code?#

Yes. Because Replay uses Visual Reverse Engineering, it focuses on the application's runtime behavior. While having source code can provide additional context, Replay can document and reconstruct logic by observing the inputs, outputs, and state changes of the running application. This is vital for systems where the original source has been lost or corrupted.

How does Replay ensure the new React code matches the legacy system's calculations?#

Replay uses a process called "Determinism Verification." By comparing the outputs of the legacy system and the new React components using the same input datasets, Replay identifies any discrepancies. For insurance underwriting systems extracting logic, this visual and data parity is essential for passing regulatory audits and ensuring actuarial accuracy.

Can Replay work with other legacy languages besides VB6?#

While this guide focuses on VB6, Replay’s visual reverse engineering engine is language-agnostic. It can be used to modernize PowerBuilder, Delphi, COBOL-based terminal screens, and early .NET applications. If a user can interact with it on a screen, Replay can document and modernize it.

What is the typical learning curve for a team using Replay?#

Most enterprise architects and senior React developers can become proficient with Replay in less than a week. The platform is designed to augment existing workflows, providing a "Blueprint" that developers can then refine and integrate into their existing CI/CD pipelines.

Ready to modernize without rewriting? Book a pilot with Replay