Published October 2026.
Direct answer: Treaty reinsurance is a standing agreement between a ceding insurer and a reinsurer under which the reinsurer automatically accepts (or automatically shares) defined classes of business written by the cedent during the treaty period, without reinsurance being negotiated policy by policy. It is the opposite of facultative reinsurance, which is placed one risk at a time. Treaty forms include proportional arrangements (quota share and surplus share) and non-proportional arrangements (excess of loss and aggregate excess of loss).
What is treaty reinsurance?
Treaty reinsurance is reinsurance governed by a treaty: a contract that sets the rules for how much business is ceded, how premiums and losses are shared or layered, and for how long the arrangement runs. Once the treaty is bound, eligible policies that meet the treaty’s definitions are covered automatically when the cedent writes them, subject to any limits, exclusions, or retention stated in the treaty wording.
The ceding company (cedent) remains responsible to its policyholders; the reinsurer reimburses or assumes share according to the treaty. Treaty reinsurance is how most primary carriers manage capacity, stabilize results on a block of business, and align capital with underwriting appetite at scale. For carrier-level context on why reinsurance exists, see Reinsurance Fundamentals: How Carriers Transfer Risk.
Exam shorthand: if the question describes automatic cession of a class or portfolio under a master agreement, that is treaty reinsurance—not facultative placement on a single large risk.
Which of the following is true of treaty reinsurance?
On licensing and fundamentals exams, “true” statements about treaty reinsurance usually turn on a small set of facts. Use this checklist against multiple-choice options.
- True: Treaty reinsurance covers defined business automatically during the treaty term when policies fall within the treaty’s scope (class, territory, limits band, etc.).
- True: The cedent and reinsurer negotiate terms once in the treaty; individual policies do not require separate reinsurance slips for each risk (unlike facultative).
- True: Treaty structures are commonly grouped as proportional (quota share, surplus share) or non-proportional (excess of loss, including aggregate forms).
- True: The cedent typically retains some portion of each risk (retention) or pays losses up to a deductible/layer attachment before reinsurance responds (non-proportional).
- False (common distractors): Treaty reinsurance is not “only for one policy,” “negotiated fresh for every loss,” or “always 100% ceded with no retention” unless the specific treaty type and wording say so (quota share can cede a fixed percentage, but surplus and XL treaties retain by design).
- False: Treaty reinsurance does not eliminate the cedent’s legal duty to policyholders; it transfers or shares insurance risk economically to the reinsurer per contract.
For treaty mechanics, commissions, and structure choice in practice, the long-form reference is Reinsurance Treaty: The Complete Guide.
Treaty vs facultative reinsurance
Facultative reinsurance is optional, individual, and transactional: the cedent offers a specific risk (or defined package), and the reinsurer accepts or declines. It is used for unusual exposures, line-size limits, or risks outside treaty scope.
Treaty reinsurance is portfolio-oriented: the reinsurer commits in advance to a rule set applied to all qualifying business written in the period.
| Dimension | Treaty | Facultative |
|---|---|---|
| Unit of placement | Class / portfolio / layer program | Single risk (or defined sub-unit) |
| Timing | Automatic when eligibility met | After offer and acceptance per risk |
| Typical use | Core book, capacity, balance sheet relief | Facilities, jumbo limits, non-standard risks |
| Exam cue | “Master agreement,” “automatic cession” | “Offered and accepted,” “one policy” |
Both can coexist on the same account: treaty handles the running book; facultative tops up what treaties exclude or cannot capacity. Broader professional framing appears in Reinsurance: The Complete Professional Guide (2026).
Quota share vs surplus share
Both are proportional treaty reinsurance: premium and losses are shared between cedent and reinsurer in fixed ratios once a risk is ceded.
Quota share treaty: The cedent cedes a constant percentage of every eligible policy (for example, 30% of premium and 30% of losses on all qualifying business). Retention is simply the complement (70% in that example). Quota share is simple, increases reinsurer share of the whole portfolio, and often pairs with a ceding commission to reimburse the cedent for acquisition and administration.
Surplus share treaty: The cedent retains a fixed dollar (or line) amount on each risk—its “retention line”—and cedes amounts above that retention in multiples of the line, up to treaty capacity. Surplus share cedes less on small risks (where retention covers the limit) and more on larger limits, so the ceded percentage varies by policy size even though the line structure is uniform.
| Feature | Quota share | Surplus share |
|---|---|---|
| Ceded proportion | Same % on each eligible policy | Varies by insured limit vs retention line |
| Retention concept | Implicit (% not ceded) | Explicit per-risk line, then cede multiples |
| Exam distinction | “Fixed percentage of all business” | “Retention line,” “number of lines” ceded |
Structure comparisons and when carriers pick quota share versus excess-of-loss layers are developed in Quota Share Reinsurance vs Excess of Loss (Treaty Structures).
Excess of loss: per-risk, per-occurrence, aggregate
Excess of loss (XL) treaties are non-proportional: the reinsurer pays only when a loss exceeds a stated threshold. Premium is not shared proportionally with losses in the same way as quota or surplus share; instead, the cedent pays reinsurance premium for capacity above retentions and deductibles.
Per-risk excess of loss (risk XL): Applies to each individual policy or each individual loss occurrence as defined in the treaty (exam questions often say “each and every loss”). The cedent retains losses up to the retention (deductible); the reinsurer pays the layer above, up to the limit.
Per-occurrence excess of loss (occurrence XL): Responds when total loss from one occurrence (one event) exceeds an attachment point. Common in property catastrophe programs where many policies are hit by one storm or earthquake. The unit of measurement is the occurrence, not each minor claim in isolation.
Aggregate excess of loss (aggregate XL): Protects the cedent when total losses accumulated in a period (often a treaty year) exceed an aggregate attachment. It is a backstop on frequency or an accumulation of retained losses after other reinsurance, not a substitute for understanding per-risk or per-occurrence towers.
Exam tip: “Proportional” means share premium and losses by ratio; “non-proportional” means pay only above attachment, usually for a defined limit. Aggregate XL adds “in the aggregate over the period” language.
Large natural-catastrophe accumulations and why occurrence towers matter for portfolios are discussed in Catastrophe Portfolio Management: Accumulation, PML.
What “treaty coverage” means in practice
Treaty coverage means a policy or loss falls within the operative treaty’s scope and is subject to its cession rules for the treaty period. “Covered by treaty” is not a policyholder-facing term on the dec page; it is an internal reinsurance accounting and claims-allocation concept.
In practice, treaty coverage implies:
- The risk meets treaty definitions (line of business, territory, policy form, size band).
- Cession applies automatically per quota, surplus, or XL wording—no separate facultative certificate is required unless the risk is specifically excluded or referred out.
- Premium ceded and loss recoveries are calculated per treaty articles (including reinstatements on XL, commissions on proportional treaties, and any reporting requirements).
- Business written outside scope stays on the cedent’s net account or needs facultative support.
Visual and narrative walkthroughs of how treaties fit carrier strategy appear in Reinsurance: Expert Video Analysis. Alternative risk transfer (including catastrophe bonds) sits outside standard treaty Q&A; treat it as a separate capital-markets tool, not a substitute for defining quota share versus XL.
Frequently asked exam questions
What is treaty reinsurance?
Treaty reinsurance is a standing agreement under which a reinsurer automatically accepts or shares defined classes of business written by a ceding insurer during the treaty period, according to fixed cession rules, without negotiating reinsurance separately for each policy.
Which of the following is true of treaty reinsurance?
True statements typically include automatic cession of eligible business under a master agreement, negotiation of terms once at treaty level, and use of proportional or non-proportional structures. It is not limited to a single policy, and it does not remove the cedent’s obligations to policyholders.
What does treaty coverage mean?
Treaty coverage means a policy or loss falls within the treaty’s scope for the period and is ceded and settled under that treaty’s proportional or excess-of-loss rules, rather than requiring facultative placement for that unit of risk.
Quota share vs surplus share—which is which?
Quota share cedes a fixed percentage of every eligible policy’s premium and losses. Surplus share cedes amounts above a per-risk retention line in multiples of that line, so the ceded proportion varies with policy limit while the line structure stays constant.
Treaty vs facultative reinsurance—what is the difference?
Treaty reinsurance covers a defined portfolio automatically under one agreement. Facultative reinsurance is placed risk by risk, with the reinsurer accepting or declining each offered exposure.
How does excess of loss differ from quota share?
Quota share is proportional: a set share of premium and loss on ceded business. Excess of loss is non-proportional: the reinsurer pays only when losses exceed an attachment point, up to a layer limit, whether measured per risk, per occurrence, or in the aggregate.