The loss-ratio trap — when a clean book gets contaminated.

Contingency income is the quiet profit center of a well-run agency — pure margin, no producer splits, no servicing overhead, flowing straight to the bottom line. It's also the synergy a careless acquisition can destroy, because contingency is calculated on the combined book's loss ratio. A buyer who acquires a high-loss agency and merges the carrier codes doesn't just inherit the acquired book's bad experience — they blend it into their own clean book and can lose contingency on everything. The trap is in the weighted-average math, and the escape is in understanding it before close.

§ 01 · The weighted-average mathHow a clean book gets pulled under.

The combined loss ratio is the sum of both books' claims divided by the sum of both books' premium — dollar-weighted by claims, not weighted in the buyer's favor. The worked example shows the danger: a $5M book at a 45% loss ratio is comfortably profitable and earning contingency, but acquiring a $2M book at 75% blends the combined $7M to roughly 54%. That single move pushes the previously-profitable book above the 50% threshold and wipes out contingency on the entire $7M, not just the acquired $2M — the acquisition's loss experience contaminates the buyer's own. The forensic discipline behind reading a target's true loss ratios is the same one covered in loss ratios; here the question is what that ratio does to the combined book.

§ 02 · Three threshold tiersWhy the cliffs matter.

The reason the weighted-average math is so dangerous is that the thresholds behave like cliffs. Below 50%, a book earns; at 50%, most carriers pay nothing; and the 45%–55% band is where tiered contingency schedules move fastest, so every point of blended loss ratio in that range shifts the payout by tens of thousands of dollars. Above 60%, the consequence escalates beyond lost contingency into active carrier scrutiny — book reviews and nonrenewals. With contingency representing 10%–30% of a mid-sized agency's total earnings, the stakes are real: a buyer who blends their way from 45% to 54% hasn't lost a little contingency on the acquired book, they've lost most of the contingency on the whole combined book, which can swamp the synergy the acquisition was supposed to deliver.

§ 03 · Merge or keep separateThe carrier-by-carrier decision.

The defense against contamination is structural, and it's not a single decision. There are two post-close options for the acquired book's carrier appointments. A code merge consolidates the seller's appointments under the buyer's agency code — the default, and the move that unlocks volume synergies, but the one that blends loss ratios. Keeping the codes separate runs them in parallel for one to three years to isolate the acquired book's claims experience — which fragments volume but preserves the buyer's clean contingency. The right answer is rarely uniform: the correct approach is a carrier-by-carrier analysis, merging for carriers where both books run well under 50% and keeping separate where the acquired book's performance is borderline or unknown. One more lever exists for buyers with scale — a "start fresh" provision, where some carriers (particularly in specialty lines) will exclude the acquired book's historical claims from the combined calculation for a defined lookback, typically the first policy year. It's almost never offered unsolicited, so a buyer has to ask. The volume synergy this contamination risk trades against is in the tier-jumping math.

§ 04 · Pre-LOI diligence and the price asymmetryWhat to pull, and what it means.

The diligence is cheap relative to the stakes — a few hours to two days depending on data cleanliness. Pull three years of current loss runs from every major carrier on the target's book, aggregated and broken out by carrier and line of business; calculate the target's loss ratio at the carrier level; compare it to the buyer's own carrier-level ratios; and run the pro-forma blended ratio under both code-merge and keep-separate scenarios. The walk-away signal is concrete: if the target sits structurally 15–20 points above the buyer's book and the target's volume is large enough to move the blended ratio, the math can defeat the deal even with clean execution everywhere else. The deeper insight is a valuation one — the same agency can be worth dramatically more to a buyer with a clean book and aligned carriers than to one facing contamination risk, so the multiple should reflect that asymmetry rather than assuming a single price for every buyer. A buyer who runs this analysis knows both whether to walk and what the target is actually worth to them.

◆