Reinsurance is insurance for insurance companies. When an insurer writes policies covering homes, cars, or businesses, it takes on financial risk with every policy it issues, and it can transfer part of that risk to another company in exchange for a share of the premiums. That second company is the reinsurer. The arrangement keeps insurers solvent after catastrophic losses and lets them cover more policyholders than their own capital reserves would otherwise support.
You will never deal with a reinsurer directly. If your house burns down, you file a claim with your insurer, and your insurer pays you. What happens behind the scenes between that insurer and its reinsurers is a separate transaction you are not part of.
How Reinsurance Works
The mechanics are simple in outline. An insurance company, called the ceding company, pays premiums to a reinsurer. In return, the reinsurer agrees to cover some share of losses when claims come in. The ceding company keeps the direct relationship with policyholders and handles claims itself. The reinsurer operates entirely in the background.
Insurers buy reinsurance for a few practical reasons. The most obvious is catastrophe protection. A single hurricane can generate billions of dollars in claims, and no insurer wants that concentrated on its own balance sheet. Reinsurance also frees up capital. Regulators require insurers to hold reserves proportional to the risk they carry, so shifting some of that risk to a reinsurer lets the ceding company write new policies without raising additional capital. Smaller and newer insurers lean on reinsurance especially hard, because it’s how they compete with larger carriers whose balance sheets can absorb bigger swings.
Because policyholders have no contract with the reinsurer, you cannot file a claim against one. The legal principle of privity of contract limits enforcement rights to the two parties that actually signed the agreement, which are the ceding company and the reinsurer.1National Association of Insurance Commissioners. Receivers Handbook for Insurance Company Insolvencies – Chapter 6 Your insurer remains fully responsible for paying your claims regardless of what its reinsurance arrangements look like. If a reinsurer fails to pay, that’s the ceding company’s problem, not yours.
Treaty and Facultative Reinsurance
Every reinsurance arrangement falls into one of two broad categories. The difference is whether the reinsurer agrees to cover a whole book of business automatically, or evaluates each risk one at a time.
Under a treaty, the ceding company and the reinsurer agree upfront that all policies fitting certain criteria will be reinsured. If an insurer signs a treaty covering its homeowners book, every qualifying homeowners policy it writes is automatically included. The reinsurer does not underwrite individual policies. It accepts the portfolio as a whole. Treaties are typically long-term arrangements that renew annually, and they cover policies the ceding company has not yet written, so long as those future policies fit the agreed risk class.
Facultative reinsurance works the opposite way. The ceding company submits a specific risk to the reinsurer, and the reinsurer decides whether to accept it. This approach is common for high-value or unusual risks that don’t fit neatly within a treaty, such as a large commercial development or an offshore energy platform. The reinsurer underwrites each submission on its own merits and can decline any risk it doesn’t want. Facultative placements are slower and more expensive than treaty arrangements because of that individual attention, but they give insurers a way to handle one-off exposures that fall outside their normal appetite.
How Losses Get Divided
Within treaty and facultative arrangements, the actual mechanics of how losses get split vary. Some agreements share risk proportionally. Others only kick in after losses cross a specified threshold. The choice depends on what the ceding company is trying to accomplish, whether that’s smoothing out routine volatility or protecting against rare but devastating events.
Quota Share
A quota share is the simplest proportional arrangement. The ceding company transfers a fixed percentage of every policy in a portfolio to the reinsurer, and the reinsurer assumes that same percentage of both premiums and claims. Under a 40% quota share, the reinsurer collects 40% of premiums and pays 40% of every claim, no matter the size.2National Association of Insurance Commissioners. Credit for Reinsurance Model Regulation On a $100,000 claim, the reinsurer pays $40,000 and the ceding company pays $60,000.
The appeal is predictability. Both parties share good years and bad years in the same proportion. This helps smaller insurers expand quickly, because they can write more policies while only retaining part of the risk. The trade-off is that in low-loss years the ceding company gives away premiums it could have kept. To offset the ceding company’s costs of acquiring and servicing the policies, quota share agreements usually include a ceding commission paid by the reinsurer.
Surplus Share
Surplus share is a related proportional structure that works a little differently. Instead of ceding a flat percentage of every risk, the ceding company keeps a fixed dollar amount on each policy, called the retained line, and cedes only the portion above that amount. If the retained line is $500,000 and the insured value is $2 million, the ceding company keeps $500,000 and cedes the remaining $1.5 million, which is 75% of the risk. The ceded share therefore varies by policy based on insured value. This makes surplus share more complex to administer than quota share, but it lets the ceding company retain more on smaller risks where its exposure is manageable.
Excess of Loss
Excess of loss reinsurance does not share losses proportionally. The reinsurer only pays when a loss exceeds a pre-set dollar threshold called the retention. If an insurer sets its retention at $1 million and buys excess of loss coverage up to $10 million, it handles any claim up to $1 million on its own. For a $4 million claim, the reinsurer covers the $3 million above the retention.
This structure is built for catastrophic exposure. An insurer handling routine auto or homeowners claims can manage those losses out of its own reserves, but a hurricane generating $50 million in claims from a single event is a different problem. Excess of loss reinsurance acts as a financial backstop for exactly that kind of scenario. Premiums reflect the probability of breaching the retention threshold and tend to fluctuate with market conditions and recent losses. Many contracts include reinstatement provisions that let the ceding company restore coverage after a loss exhausts the original limit, usually for an additional premium.
Retrocession: Reinsurance for Reinsurers
Reinsurers face the same concentration risk as the primary insurers they cover. A reinsurer that takes on large catastrophe exposures from dozens of ceding companies could see a single event threaten its solvency. Retrocession is the industry’s term for a reinsurer buying its own reinsurance from another reinsurer, called the retrocessionaire. The mechanics mirror a standard reinsurance transaction: the reinsurer cedes a portion of the risk it has already assumed and pays a premium for the protection.
Retrocession creates a chain of risk transfer that can extend several layers deep. After major catastrophes, retrocession capacity tightens because retrocessionaires are paying claims across many clients at once. That tightening ripples through the market. Reinsurers pass higher costs to ceding companies, who pass them to policyholders through premium increases.
What Happens If a Reinsurer Fails
A reinsurer’s insolvency creates a cascading problem, though not directly for policyholders. The ceding company still owes its customers the full amount of every valid claim. The reinsurer’s inability to pay does not reduce the ceding company’s obligations by a single dollar. If a large share of the ceding company’s risk was placed with the now-insolvent reinsurer, the financial strain can be severe enough to threaten the ceding company itself.
The ceding company becomes a creditor in the reinsurer’s liquidation and has to get in line with everyone else the reinsurer owes. Recoveries in these proceedings are often a fraction of the amounts owed, and the process can drag on for years. State insurance guaranty associations, which protect policyholders when a primary insurer fails, do not cover reinsurance recoverables. They cover only direct insurance.1National Association of Insurance Commissioners. Receivers Handbook for Insurance Company Insolvencies – Chapter 6 The ceding company cannot look to a guaranty fund to make up the shortfall.
This is why regulators impose capital and collateral requirements on reinsurers, and why ceding companies pay close attention to reinsurer credit ratings. A poorly rated reinsurer offering cheaper premiums might look attractive in the short term, but the savings evaporate if it cannot pay claims when it matters.
Why Reinsurance Affects Your Premiums
If you have never heard of reinsurance before, you might wonder why any of this matters to you. The connection is direct. What your insurer pays for reinsurance is baked into the premiums you pay for homeowners, auto, or business coverage. When reinsurance is cheap and widely available, insurers can offer more coverage at lower prices. When reinsurance markets tighten, usually after a year of major natural disasters, those higher costs get passed along to you.
This has become more visible in recent years. Homeowners in areas prone to hurricanes, wildfires, or severe storms have seen sharp premium increases driven in part by rising reinsurance costs. In some markets, insurers have pulled out entirely because they could not secure affordable reinsurance for the concentration of catastrophe risk they were carrying. Without reinsurance backstopping them, insurers are either unwilling to write policies or forced to charge more than consumers expect to pay. The availability of reinsurance, quietly, shapes where insurance is offered, what it costs, and how much coverage you can actually buy.