How to Calculate Marketing ROI for a Personal Injury Firm When Settlements Take 18 Months

You spent $200,000 on lead generation last month. Your managing partner wants to know if it worked. But the cases you signed won't settle for another 12 to 18 months — so what number do you give them?

This is the core ROI problem for PI firms. Standard marketing math assumes revenue follows spend within days or weeks. In personal injury, the lag is 6 to 18 months on typical cases, and 2 to 3 years on complex ones. Plug this month's settlements against this month's spend and you get a number that means nothing.

Three methods actually work. Here's how to use each one — and which to reach for depending on what decision you're trying to make.

Why Standard ROI Formulas Break for PI Firms

The standard formula:

ROI = (Revenue Generated — Marketing Cost) / Marketing Cost

It works when revenue follows spend quickly. E-commerce: same day. SaaS: 30 to 90 days. Personal injury: 6 to 18 months — longer for complex cases. That gap produces two failure modes most PI marketing directors have already experienced:

• Failure mode 1 — mismatched periods:Dividing this month's settlements by this month's spend. Those settlements reflect decisions made a year ago. The ROI number you get is meaningless for any current decision.
• Failure mode 2 — waiting for closure:Refusing to report ROI until cases settle. By the time the data is “clean,” it's too late to act on it.

The fix isn't a better spreadsheet formula. It's choosing the right method for what you're trying to answer.

Method 1: The Cohort ROI Method (Most Accurate)

The cohort method is the gold standard. It ties every marketing dollar spent in a given month to the actual settlement outcomes of cases signed that month — no mismatched periods, no estimates.

How It Works

Define a cohort by the month cases were signed. Your “February 2025 cohort” is every case signed in February 2025. Then:

1. Record total marketing spend for February 2025. If you spent $180,000 across all vendors and signed 60 cases, that's the cohort's acquisition cost.
2. Track each case in that cohort through to settlement. As they close, log the gross settlement and net attorney fee.
3. Calculate ROI as the cohort matures: net fees collected ÷ $180,000 spent.

A firm that spends $180,000, signs 60 cases, and collects $1.4 million in net fees from that cohort has a cohort ROI of 7.8x. Every dollar spent returned $7.78.

The Tradeoff

Cohort ROI is accurate but slow — you need 12 to 18 months for a cohort to be meaningful, 24 months for it to be complete. That's too slow for in-month budget calls. Use it for annual reviews, vendor evaluations, and proving marketing's value to managing partners.

Method 2: The Rolling Window Method (Most Practical)

You can't wait 18 months for every partner conversation. The rolling window method gives you a defensible ROI number today.

How It Works

Match total marketing spend over a trailing 18-month period against total net settlement revenue over the same 18-month period.

Example: September 2023 through February 2025, your firm spent $3.2 million on marketing and collected $19.5 million in net fees. Rolling 18-month ROI: 6.1x.

The attribution isn't perfect — February 2025 settlements came from cases signed months earlier. But over an 18-month window, timing effects largely cancel out. The result is stable and defensible even if it's not exact.

When to Use It

• Partner reporting and board presentations
• Budget defense and annual planning
• Year-over-year benchmarking

It blends all spend together, so it won't tell you which vendors are pulling their weight. That requires the next method.

Method 3: Projected ROI Using Case Value Estimates (For Real-Time Use)

Both cohort and rolling window methods require settled cases. Neither tells you whether last month's spend was working. Projected ROI fills that gap — it estimates settlement value from signed cases using your historical averages, so you can calculate ROI before a single case closes. This is where case value analytics pay for themselves.

How to Build the Projection

Start with your historical average net fee per signed case by case type:

• Auto accident cases: $14,500 average net fee
• Slip and fall cases: $11,200 average net fee
• Mass tort cases: $8,800 average net fee

When you sign new cases, assign projected values by type. A month where you sign 40 auto cases and 15 slip-and-fall cases produces a projected portfolio of $748,000. Then:

Projected ROI = Projected case value portfolio / Marketing spend that month

Spend $200,000 to sign cases worth an estimated $748,000 in net fees, and your projected marketing ROI is 3.7x. As those cases settle, compare actual against projected — and each cycle your averages get sharper.

The Key Caveat

This method is only as accurate as your historical settlement data. Small samples and undifferentiated case types make the projections noisy. Build your averages on at least 50 closed cases per type before relying on them for vendor decisions.

How to Calculate ROI at the Vendor Level

Firm-level ROI tells you whether marketing is working. Vendor-level ROI tells you where to put next month's budget.

Same formula, applied per vendor:

Vendor ROI = Net fees from vendor's cases / Spend with that vendor

The prerequisite: lead source tagging that follows a case from first contact through to settlement. Without it, you can't connect a check to the vendor who originated it.

When you have the data, the differences are rarely subtle. Here's a simplified example from a mid-sized PI firm spending $155K/month across three vendors:

• Vendor A: $60K/month, 25 signed cases, $425K projected net fees — 7.1x ROI
• Vendor B: $50K/month, 18 signed cases, $210K projected net fees — 4.2x ROI
• Vendor C: $45K/month, 12 signed cases, $108K projected net fees — 2.4x ROI

Vendor C is taking 29% of the budget, delivering 23% of the cases, and generating the worst ROI of the three. The conversation isn't whether to cut it — it's how fast you can move that $45,000 to Vendor A.

Benchmarks: What Is a Good Marketing ROI for a PI Firm?

Public data is sparse, but here's what the ranges look like in practice:

• Under 3x: Below breakeven once you factor in case costs, overhead, and referral splits. Investigate before cutting spend — the problem may be in intake conversion, not the leads.
• 3x–5x: Acceptable but not optimized. Vendor mix or intake quality is likely leaving money on the table.
• 5x–8x:Strong. Marketing is working. The job shifts to scaling what's already producing.
• 8x+: Excellent — and uncommon. Typically reflects both strong intake conversion and a high-value case mix.

These numbers vary by practice area. Mass tort firms often run lower per-case ROI at higher volume. Catastrophic injury practices may run lower volume but hit 10x or higher on the cases they sign.

Practical Steps to Start Calculating ROI Today

You don't need perfect data to start. Build toward accuracy in stages:

1. Week 1: Pull the last 18 months of marketing spend and net settlement revenue. Calculate your rolling window ROI. This gives you a baseline — a number you can defend or set out to improve.
2. Month 1: Audit your intake system for lead source tagging. Find where source data is getting lost. Fix the protocol so every new lead enters with a vendor tag that follows it through intake.
3. Month 3:Three months of clean tagging is enough to calculate cost per signed case by vendor. That's the first half of vendor ROI — and already more than most firms have.
4. Month 6:Start cohort tracking. Each month's signed cases becomes a cohort; track their settlement outcomes forward from here.
5. Month 18+: Your first cohorts are closing out. You can now calculate actual vendor-level ROI from real settlement data — and compare it against the projected ROI you built in Month 3.

What to Do With the Number

A methodology-backed ROI number changes the nature of every budget conversation. When a marketing director walks into a partner meeting with a defensible 6.1x rolling ROI and vendor-level projections showing where the spread is, the discussion stops being about spend and starts being about where to invest more.

• Vendor negotiations anchor to outcome data, not volume promises
• Budget cuts have a rationale — and the math to back them
• Acquisition cost targets come from actual case economics, not gut feel
• Marketing earns a seat at the strategy table, not just the expense line

The 18-month lag is real. It's also not an excuse. It's the reason to build a methodology that accounts for it — so you're making better decisions every quarter instead of waiting for the data to feel complete. RevenueScale's marketing ROI platform is built specifically for this problem: cohort tracking, projected case value, and settlement data connected back to originating lead sources.