Loss-ratio blending — the 60% gate on the combined book.

Tier-jumping is the upside a carrier premium map reveals; loss-ratio blending is the downside it must check first. The contingency gate is binary and merciless — and crucially, it's applied to the combined book at the agency-code level, so a high-loss acquired book doesn't just lose its own contingency, it can drag the buyer's clean book over the gate and forfeit contingency on everything. The map is where a buyer catches this before merging the codes.

§ 01 · The 60% gateBinary, at the code level.

The 60% loss-ratio gate is the standard contingency ceiling, and two features make it dangerous. It's binary — 59% qualifies fully, 61% forfeits all contingency with no partial credit, so the gate is a cliff, not a slope. And it's enforced at the agency-code level — if two agencies' books report under one consolidated carrier code, the carrier blends them before applying the gate. That second feature is the whole trap: a buyer's clean 40% book and a target's high-loss book, merged under one code, are tested as a single blended ratio. So the code-architecture decision (consolidate versus keep separate) directly controls whether the trap can spring, which is the subject of agency-code architecture. The premium map's job here is to model the blended ratio per carrier before the codes merge.

§ 02 · The blending scenariosWhere the trap springs.

The blending math is what the map computes, and it shows that the danger is volume-weighted, not just loss-ratio-weighted. A buyer at $10M and a 40% loss ratio has enough clean premium to absorb a small high-loss book: a $2M target at 80% blends to 46.7% (paid claims $5.6M ÷ $12M premium), and even a $2M target at a brutal 110% blends to only 51.7% — both safely under the gate. The trap is when the high-loss book is large: a $5M target at 110% blends the combined $15M to 63.3%, over the gate, and contingency is forfeited on the entire merged book. That's the negative-synergy phenomenon — the combined entity earns less contingency than the two agencies did apart, the day before closing. A buyer who runs the blend on the map sees it; one who credits the tier-jump without checking the gate books a synergy that the gate erases. The synergy-lens framing of this trap is in the loss-ratio trap.

§ 03 · Three trap patternsHow a clean ratio hides it.

The trap is dangerous because a clean book-level loss ratio can hide it, and three patterns are the usual culprits. The concentration trap — a clean overall ratio masks one carrier (say 35% of premium) running at 85%, so the agency-level number looks fine while the carrier-level number is over the gate. The volume-imbalance trap — at a carrier where the target dominates the premium weight, the target's loss ratio effectively becomes the combined ratio, so the buyer's clean book can't dilute it. And the pending-claim trap — a large reserved-but-unpaid claim doesn't yet hit the paid loss ratio, but it's the carrier's own forward forecast, so it springs the gate next year. A reserved claim over $100,000 deserves a documented narrative (claimant, event, expected resolution timing), because a single large reserve can tip the next year's ratio over the gate. The map has to be built per carrier, not just at the agency level, to catch all three.

§ 04 · The loss-run disciplineWhat to pull, what it must show.

Catching the trap requires the right data: carrier-issued loss runs covering 3–5 years, from every carrier writing 5%+ of the book (a lower threshold for concentrated books). The mandatory columns are paid claims, reserved claims, claim frequency, the 3-year trend, and carrier commentary — because the reserved column and the carrier's commentary are where the forward-looking risk lives, invisible in a paid-only ratio. With those loss runs, a buyer builds the combined loss ratio per carrier and tests each against the 60% gate before deciding how to architect the codes, which is the only way to see the concentration and volume-imbalance traps. The discipline is straightforward but non-negotiable: pull the loss runs early, model the blend per carrier on the premium map, flag any reserved claim over $100K, and let the gate test drive the code-architecture decision. Skip it, and the tier-jump synergy the map promised can be erased by a gate the buyer never modeled. The lookback discipline behind the loss runs is in the three-year lookback.

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