Cross-System VAT Calculation

The data needed to calculate VAT was split between two independent systems that shared no common logic and no direct integration.

A deterministic process that pulls what it needs from both sources, reconciles them and produces one repeatable result.

Previously around 25 minutes of manual work per customer. Across 11 customers that is roughly 4 hours 35 minutes for one full cycle.

A professional project. Client names, system names and real data are deliberately not shown.