Start with monthly process volume, multiply by average staff time and cost, then add the cost of errors and opportunities lost to slow replies. That is the current-state cost.
Model a realistic scenario
Do not assume 100% automation. Use a conservative share of work completed, then add human review, platform usage and maintenance.
Measure after launch
Track cycle time, conversion, human handoffs and error rate. If those numbers do not improve, fix the workflow before adding more features.