What is the WIP aging report?

A WIP aging report shows unbilled work in process organized by how long it has remained unbilled, typically in aging buckets like current, 31 to 60 days, 61 to 90 days, and over 90 days. Old WIP often signals billing problems. For professional service firm owners, the WIP aging report reveals cash flow issues before they hit your bank account and highlights projects that need invoicing attention.

Key characteristics

• Tracks unbilled work by age

• Aging buckets show delays

• Early warning for cash flow

• Identifies problem projects

• Supports billing discipline

• Monthly review recommended

Why it matters for professional service firms

Work sitting unbilled too long often never gets billed at full value. Clients question old charges. Details get forgotten. Disputes arise. If your WIP aging shows substantial balances over 60 days, something is wrong with your billing process. This report catches problems while they are still fixable.

Real-world example

Lisa reviewed her monthly WIP aging: current (0 to 30 days) $85,000, 31 to 60 days $28,000, 61 to 90 days $14,000, over 90 days $22,000. Total WIP: $149,000. The $22,000 over 90 days concerned her. Investigation revealed two projects with scope disputes. One got written down $8,000 and invoiced—the other required client negotiation. Without the aging report, she would have noticed only when cash ran short.