Custom Engagement & Retainer Billing System for a Multi-Consultant Advisory Group

Overview

Built a custom billing system for a multi-consultant advisory group juggling a mix of hourly engagements, fixed-fee projects, and monthly retainers that its off-the-shelf invoicing tool couldn't cleanly handle. The system tracks billable time and project milestones per consultant, automatically generates the correct invoice type based on each client's contract terms, and flags retainer clients approaching their monthly hour cap. This replaced a process where the office manager was manually reconciling three different billing structures in a single spreadsheet every month. Partners now get a real-time view of billable utilization across the whole team instead of finding out at month-end. A multi-consultant advisory group's office manager was manually reconciling three different billing structures — hourly, fixed-fee, and retainer — in a single spreadsheet every month, with partners finding out about utilization only at month-end. We built a custom billing system tracking billable time and milestones per consultant, automatically generating the correct invoice type per contract terms and flagging retainer clients approaching their monthly hour cap. We reviewed every current contract type with the office manager to understand exactly how each billing structure's edge cases were being handled manually, then modeled the system around all three rather than picking one and forcing the others to fit. It was validated against a full month of past billing data before going live. Month-end billing reconciliation time dropped by an estimated 70%, and partners now have real-time visibility into consultant utilization across the whole team instead of finding out at month-end.