Economics & ClaimsCore

Net Retained Lines

What's left after every cession

The amount of risk an insurer actually keeps for its own account after every layer of outward reinsurance is applied — its true net exposure to any one loss.

Open the interactive version → definition, quiz, structure diagram and progress tracking

Definition

Net retained lines describe an insurer's final net retention per risk after every layer of outward reinsurance — quota share, surplus share, excess-of-loss — has been applied on top of each other. It is the number that matters for understanding true net exposure: not what the insurer originally underwrote, but what is actually left on its own books after every cession. Insurers set a maximum net retained line for each class of business, and any risk that would exceed it after normal reinsurance must be reduced further, typically through facultative reinsurance.

It is measured after every layer of outward reinsurance has been applied, not before — the number that matters is what is left, not what was originally underwritten.
Insurers set a maximum net retained line for each class of business, and any risk exceeding it must be reduced further through additional, typically facultative, reinsurance.
Keeping net retained lines consistent across similar risks is what makes an insurer's retained portfolio behave predictably, rather than being skewed by a handful of oversized outliers.

Worked example

An insurer writes a $10M property risk, cedes 40% to a quota share and a further half of its remaining share to a surplus treaty, leaving a net retained line of $3M — the figure that actually matters for its own retained exposure.

Scenario · figures in USD

From a $10M risk down to the true net line

An insurer underwrites a $10M commercial property risk and applies two layers of proportional reinsurance in sequence.

Original gross line underwritten	$10M
After 30% quota share cession	$7M retained
After a further surplus treaty cession of half the remainder	$3.5M retained
Insurer's net retained line on this risk	$3.5M
Insurer's maximum net retained line for this class	$4M
Result	Within the maximum — no further facultative reinsurance needed

So whatThe gross $10M line says almost nothing about the insurer's true exposure — only the $3.5M net retained line, after every cession, reflects what it actually keeps.

Check your understanding

What does "net retained line" measure?

The insurer's final net retention on a risk after every layer of outward reinsurance has been applied. Net retained line is what remains with the insurer after all its outward reinsurance cessions are applied — its true net exposure, not its original gross line.

What happens when a risk's net retained line, after normal reinsurance, would exceed the insurer's maximum for that class?

The excess must be reduced further, typically through facultative reinsurance. When normal treaty reinsurance leaves a net retained line above the insurer's set maximum for that class, the excess is typically placed facultatively to bring it back within limits.

Word problem

An insurer underwrites a $12M risk. It cedes 25% to a quota share, then cedes half of what remains to a surplus treaty. Its maximum net retained line for this class is $4.5M. What is the net retained line after both cessions, and does it need further facultative reinsurance?

Show a hint

Apply each cession in sequence to the remaining amount, not both to the original $12M separately.

Reveal the worked answer

After 25% quota share: $12M × 75% = $9M retained.
After ceding half the remainder to the surplus treaty: $9M × 50% = $4.5M retained.
The insurer's net retained line on this risk is exactly $4.5M.
Since the maximum allowed net retained line for this class is also $4.5M, the risk sits exactly at the limit — no further facultative reinsurance is required.

The net retained line comes to exactly $4.5M after both cessions are applied in sequence, which sits right at (not above) the insurer's $4.5M maximum for this class — so no further facultative reinsurance is needed, though there is no room left for the retention to be any larger on a similar risk.

Related terms

Part of the Treaty Reinsurance guide, where this term is explained alongside every other treaty metric.