Cession bordereau
A statement detailing policy by policy the risks ceded to a treaty, with sums insured, premiums and shares.
Textbook case: on a 34,000 line bordereau with 19% lacking a usable postal code, correcting 6,400 policies lifts the 200 year probable maximum loss from 74 to 91 million euros, and the reinsurer cuts its share from 11 to 7%. A cession bordereau lists, line by line, the risks ceded to a treaty. Each policy carries its sum insured, premium, ceded share and the characteristics needed for exposure analysis. It is indispensable on surplus treaties, where the cession is computed policy by policy, and on any business whose geographic accumulation the reinsurer wants to measure. It solves a problem of knowing actual exposure. A reinsurer holding only aggregates cannot know whether a thousand policies cluster in one seismic zone, and its catastrophe model then runs on distribution assumptions rather than on data. Bordereau quality is the chronic weak point of the chain: incomplete addresses, missing zone codes, absent values. Recent treaties expressly condition certain covers on the delivery of compliant bordereaux. The errors and omissions clause covers only good faith failures, not the systematic absence of data.
A reinsurer receives a 34,000 line bordereau in 2026, of which 19 percent carry no usable postal code. Its model assigns those risks to the regional centroid by default, which understates coastal accumulation. Restating only the corrected lines, covering 6,400 policies, lifts the two hundred year probable maximum loss from 74 to 91 million euros, and leads the reinsurer to cut its share from 11 to 7 percent.
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