Most PI firms know their cost per case. Very few know their cost per case that actually settles. The gap between those two numbers is attrition — and it is quietly destroying your marketing ROI.
Case attrition happens when a signed case never produces revenue. The client stops responding. The injuries don't support a claim. The case is withdrawn before settlement. Whatever the reason, the acquisition cost of that case is a total loss. And if you are not measuring it, you are systematically underestimating how much your marketing actually costs.
The Attrition Cost Model
Here is the framework. Every dollar you spend on marketing acquires a portfolio of signed cases. Some of those cases will settle and generate revenue. Some will not. The ones that do not still cost you money — acquisition cost, intake labor, case management overhead, and attorney time before the file is closed.
The real cost of a viable case is not your cost per signed case. It is your cost per signed case divided by the percentage of cases that actually produce revenue. That adjustment changes the math significantly.
$4,000
True Cost Per Viable Case
At 25% attrition with $3,000 CPC
Breaking Down the Numbers
Take a firm spending $150,000 per month across its lead vendors, signing 50 cases per month. That is a $3,000 cost per signed case. Straightforward.
Now apply a 25% attrition rate — which is conservative for many PI firms. Of those 50 signed cases, only 37 or 38 will ever produce revenue. The $150,000 in marketing spend is now spread across 37 viable cases instead of 50. Your true cost per viable case is $4,054 — not $3,000.
Monthly Spend
$150,000
Total marketing budget
Cases Signed
50
$3,000 cost per signed case
Attrition Rate
25%
Cases that never settle
Viable Cases
37.5
Cases that produce revenue
That $1,054 gap — the difference between your reported CPC and your actual cost per revenue-producing case — is money your firm has already spent and will never recover. At 50 cases per month, that is $52,700 per month in hidden cost. Over a year, $632,400.
The Three Layers of Attrition Cost
Attrition does not just inflate your acquisition cost. It creates three distinct layers of financial damage.
Layer 1: Acquisition Cost of Non-Viable Cases
This is the most obvious layer. You paid to acquire cases that will never produce revenue. At 25% attrition and $3,000 CPC, that is 12.5 non-viable cases per month at $3,000 each — $37,500 per month in pure acquisition waste.
Layer 2: Operational Cost Before Withdrawal
Non-viable cases do not fail on day one. They consume resources before they are identified and closed. Intake processing, initial attorney review, medical record requests, client communication attempts, file setup in your case management system. Conservative estimate: $400 to $800 per case in operational cost before withdrawal.
At 12.5 non-viable cases per month and $600 average operational cost, that is another $7,500 per month — $90,000 per year — in operational waste on cases that never had a chance.
Layer 3: Compounded Effect on Cost Per Settled Case
This is where the math gets uncomfortable. Your viable cases must absorb not only their own acquisition cost, but also the acquisition and operational costs of the non-viable cases. Every point of attrition increases the burden on the cases that actually perform.
Acquisition Waste
$450,000
12.5 non-viable cases × $3,000 × 12 months
Operational Waste
$90,000
12.5 cases × $600 ops cost × 12 months
Total Annual Cost
$540,000
Hidden cost of 25% attrition
How Attrition Varies by Source — And Why That Matters
Not all lead sources have the same attrition rate. This is where the financial framework becomes a decision-making tool.
A vendor delivering cases at $2,800 CPC with 15% attrition has a true cost per viable case of $3,294. A vendor delivering at $2,500 CPC with 35% attrition has a true cost per viable case of $3,846. The “cheaper” vendor is actually 17% more expensive when you account for attrition.
Vendor A
$3,294
$2,800 CPC × 15% attrition = lower true cost
Vendor B
$3,846
$2,500 CPC × 35% attrition = higher true cost
If you are evaluating vendors on cost per signed case alone, you are making budget allocation decisions with incomplete data. The vendor that looks cheapest on a CPC basis may be the most expensive when measured against revenue-producing outcomes.
The Attrition-Adjusted Formula
Here is the calculation your firm should be running for every lead source, every quarter:
True Cost Per Viable Case = (Total Spend on Source + Operational Cost of Non-Viable Cases from Source) / Number of Cases from Source That Produce Revenue
This requires three data points most PI firms do not connect today: marketing spend by source, case outcome by source (settled vs. withdrawn/dismissed), and operational cost per case file. Without all three, you cannot calculate this number. And without this number, you cannot make informed vendor allocation decisions.
What a 5-Point Attrition Reduction Is Worth
Reducing attrition from 25% to 20% on a $150,000 monthly spend with 50 signed cases changes the math materially.
Before (25%)
$4,054
Cost per viable case
After (20%)
$3,750
Cost per viable case
Monthly Savings
$11,400
$304 × 37.5 viable cases
Annual Savings
$136,800
Without spending one additional dollar
That $136,800 in annual savings comes without increasing your marketing budget by a single dollar. It comes from improving the yield on spend you are already making. For most firms, a 5-point attrition reduction is worth more than a $500 reduction in cost per signed case — because it improves every case in the portfolio, not just the marginal one.
Why This Framework Matters for Partner Conversations
When a managing partner asks “What is our cost per case?” and the marketing director answers $3,000, both people believe the conversation is about the same number. It is not. The partner is thinking about cost per case that generates revenue. The marketing director is reporting cost per signed case — which includes cases that will never produce a dollar.
The attrition-adjusted framework closes that gap. It gives leadership the number they actually need: what does it cost us to acquire a case that will generate fee revenue? That is the number that belongs in budget conversations, vendor reviews, and profitability analysis.
$632,400
Annual Hidden Cost
For a firm with 25% attrition at $3,000 CPC
Building This Into Your Reporting
To operationalize the attrition cost model, you need to track three things consistently: marketing spend by source, case disposition by source (settled, withdrawn, dismissed, pending), and the operational cost incurred on non-viable cases before closure.
Most firms can estimate operational cost per non-viable case with reasonable accuracy. The harder part is connecting case disposition back to the original lead source — especially when settlements happen 6 to 18 months after signing. That connection is where the 6-18 month settlement lag creates the biggest reporting blind spot in PI marketing.
RevenueScale's Case Analytics tracks every case from lead source through disposition — including attrition by source, operational cost per non-viable case, and true cost per viable case — so you can see the full financial picture, not just the CPC your vendors report.