Every PI marketing director knows their cost per signed case. It is the number that shows up in vendor reports, budget reviews, and partner presentations. But cost per signed case is not the number that determines whether your marketing is profitable. Cost per viable case is.
A viable case is a signed case that produces revenue — one that moves through your pipeline and results in a settlement or verdict that generates a contingency fee. The gap between cost per signed case and cost per viable case is your attrition premium. And for most PI firms, that premium is larger than they realize.
Related guide: See our definitive guide to cost per case for PI firms — calculation formula, benchmarks by firm size and lead source, and step-by-step tracking methodology.
Defining the Terms
Cost Per Signed Case (CPC): Total marketing spend on a source divided by the number of cases signed from that source. This is what most firms track and what most vendors report.
Cost Per Viable Case (CPVC): Total marketing spend on a source divided by the number of cases from that source that actually produce fee revenue. This accounts for withdrawals, dismissals, non-responsive clients, and cases that fail to meet liability or damages thresholds.
The formula is straightforward: CPVC = CPC / (1 − Attrition Rate). A $3,000 CPC with 12% attrition produces a $3,409 CPVC. A $3,000 CPC with 35% attrition produces a $4,615 CPVC. Same cost per signed case. Wildly different cost per dollar of revenue.
The Same CPC, Two Very Different Outcomes
Consider two vendors, both delivering signed cases at $3,000 CPC. On a standard vendor scorecard, they look identical. But when you track what happens to those cases over the next 12 to 18 months, the picture changes dramatically.
| Vendor A | Vendor B | |
|---|---|---|
| Cost Per Signed Case | $3,000 | $3,000 |
| Monthly Spend | $30,000 | $30,000 |
| Cases Signed / Month | 10 | 10 |
| Attrition Rate | 12% | 35% |
| Viable Cases / Month | 8.8 | 6.5 |
| Cost Per Viable Case | $3,409 | $4,615 |
| Annual Wasted Spend | $43,200 | $126,000 |
Vendor A delivers 8.8 viable cases per month at $3,409 each. Vendor B delivers 6.5 viable cases at $4,615 each. That is a 35% difference in true acquisition cost — completely invisible if you are only looking at cost per signed case.
Over a year, Vendor B wastes $126,000 in marketing spend on cases that never produce revenue. Vendor A wastes $43,200. The difference — $82,800 — is the annual cost of not measuring attrition by source.
Why This Blind Spot Exists
The gap between CPC and CPVC is invisible for two reasons. First, attrition data lives in your case management system, not in your marketing reports. Vendors report leads delivered and cases signed. They do not report — and often do not know — how many of those cases eventually settle. The data that connects marketing spend to revenue outcome sits in a different system, managed by a different team, on a different timeline.
Second, the settlement lag in PI makes the feedback loop painfully slow. A case signed in January may not settle until July of the following year. By the time you know whether a vendor's cases are viable, you have already spent 12 to 18 months of budget based on CPC alone.
How Attrition Rates Vary Across Sources
Attrition is not uniform. Different lead sources produce cases with different viability profiles, and those differences are predictable once you start measuring them.
Attorney referrals typically have the lowest attrition — 5% to 10% — because the referring attorney has already screened for case viability. Digital lead aggregators often sit at the other end, with attrition rates of 25% to 40%, because the qualification criteria are broader and the client's commitment level is lower at the point of contact.
These ranges are illustrative. Your firm's actual numbers will depend on your intake process, case criteria, and the specific vendors in your portfolio. The point is not the benchmark — it is that you need to know your own numbers by source.
The Budget Allocation Problem
When you allocate budget based on CPC, you are optimizing for the wrong variable. You are directing more spend toward sources that produce signed cases cheaply, regardless of whether those cases produce revenue.
A rational budget allocation optimizes for cost per viable case — or better yet, cost per dollar of settlement revenue. That requires connecting three data sets: marketing spend by source, case disposition by source, and settlement value by source. When you connect those three, your vendor rankings almost always change.
| CPC Rank | CPVC Rank | Difference | |
|---|---|---|---|
| Vendor C ($2,400 CPC, 8% attrition) | #1 (cheapest) | #1 ($2,609 CPVC) | No change |
| Vendor A ($3,000 CPC, 12% attrition) | #3 | #2 ($3,409 CPVC) | Up 1 rank |
| Vendor D ($2,700 CPC, 28% attrition) | #2 | #3 ($3,750 CPVC) | Down 1 rank |
| Vendor B ($3,000 CPC, 35% attrition) | #3 (tied) | #4 ($4,615 CPVC) | Down 1 rank |
Vendor D — which looked like the second-best option on a CPC basis — drops to third when attrition is factored in. Vendor A moves up. The budget allocation decision changes, and with it, the firm's effective marketing ROI.
What to Measure and How Often
Measuring cost per viable case requires a cohort approach. For each month of signed cases, track the disposition of every case from each source over 12 to 18 months. As cases settle, are withdrawn, or are dismissed, update the attrition rate for that source and that cohort.
Early indicators are available sooner than final disposition. Client non-responsiveness in the first 60 days, failure to provide medical records, and low initial injury severity are all leading indicators of attrition. Firms that track these early signals can estimate source-level attrition within 90 days of signing, rather than waiting 12 to 18 months for final outcomes.
Review cost per viable case quarterly at minimum. Update the calculation whenever a meaningful number of cases from a cohort reach final disposition. And use it — alongside CPC and settlement value — as a primary input to vendor budget allocation.
Closing the Blind Spot
Cost per signed case is a starting point, not a finish line. It tells you what you paid to get a case in the door. It does not tell you what you paid to get a case that generates revenue. Until you measure the gap between CPC and CPVC by source, you are making six-figure budget decisions with half the data.
The firms that track cost per viable case consistently find that their vendor portfolio looks different than they expected. Some “expensive” vendors turn out to be efficient. Some “cheap” vendors turn out to be the most costly line item in the budget. The data is there. The question is whether you are connecting it.
RevenueScale's Case Analytics connects your marketing spend to case disposition and settlement data automatically — so you can see cost per viable case by source without building a spreadsheet that takes 15 hours a week to maintain.