Aggregate Stop-Loss Attachment Calculator
Estimate an aggregate stop-loss attachment point from changing enrollment, expected claims, and either a corridor or quoted factor. Add an actual eligible-claims scenario to see the reimbursement estimate and employer-retained claims.
Aggregate attachment point$675,000.00
- Average enrollment
- 90
- Projected member months
- 1,080
- Expected aggregate-eligible claims
- $540,000.00
- Effective attachment factor PEPM
- $625.00
- Corridor above expected claims
- $135,000.00
- Claims above attachment
- $75,000.00
- Estimated aggregate reimbursement
- $75,000.00
- Employer-retained eligible claims
- $675,000.00
Enrollment is assumed to change evenly from the starting count to the ending count.
Eligible claims are assumed to be after specific reimbursements and all contract adjustments entered by the user.
How to use this calculator
- Choose whether the attachment comes from the expected-claims corridor or a carrier-quoted PEPM factor.
- Enter the starting and ending enrolled employee counts for the covered period.
- Enter expected aggregate-eligible claims PEPM and the corridor or quoted factor from the quote.
- Enter actual aggregate-eligible claims and the maximum aggregate benefit to model a reimbursement scenario.
How aggregate stop-loss attachment is calculated
Aggregate stop-loss limits an employer's liability for eligible claims across the covered group. The attachment point is the amount of aggregate-eligible claims the employer retains before aggregate coverage may reimburse the excess. It is separate from the specific deductible, which applies to claims for an individual person.
This calculator first estimates the enrollment exposure in member months. Let Ns be starting enrollment, Ne ending enrollment, and m covered months. It assumes enrollment changes evenly:
average enrollment = (Ns + Ne) ÷ 2
member months = average enrollment × m
With expected eligible claims PEPM x, expected aggregate-eligible claims are E = member months × x. In corridor mode, the attachment is A = E × (C ÷ 100), where C is the aggregate corridor. In quoted-factor mode, it is A = member months × f, where f is the carrier's quoted aggregate factor PEPM.
The effective attachment factor is A ÷ member months when there are member months. The corridor dollars are A − E. For the entered claims scenario L, claims above attachment are max(0, L − A); estimated reimbursement is that amount limited to the maximum aggregate benefit B: min(max(0, L − A), B).
What moves the attachment point
Enrollment and the length of the projection drive member months. A growing group produces more member months under the linear assumption, so both an expected-claims attachment and a quoted-factor attachment rise. Expected claims PEPM and the corridor determine the attachment in corridor mode. In quoted-factor mode, the quoted factor controls the attachment even when it is above or below the expected claims PEPM.
The actual-claims result is only as useful as the claims definition. Enter aggregate-eligible claims after specific reimbursements, exclusions, and any adjustments the contract requires. The maximum benefit can cap reimbursement even when claims are far above attachment.
What this calculator leaves out
This is a planning estimate rather than a premium quote, coverage recommendation, or reimbursement determination. It uses a straight-line enrollment change instead of actual monthly census counts. A carrier may apply minimum attachments, monthly accommodation, terminal liability, contract-basis rules, run-in or run-out claims, incurred-versus-paid timing, lasers, exclusions, and its own rounding or adjudication rules.
Review the signed policy and the carrier's attachment and claims calculations before relying on a result. A 12/12 contract and a 12/15 contract can cover claims under different incurred and paid timing rules, even when the annual attachment looks similar.
Worked example
Suppose enrollment grows evenly from 80 to 100 employees over 12 months. Average enrollment is 90, producing 1,080 member months. At $500 expected eligible claims PEPM, expected claims are $540,000.
With a 125% corridor, the attachment is $540,000 × 1.25, or $675,000. If actual aggregate-eligible claims are $750,000, claims exceed attachment by $75,000. With a $1,000,000 maximum aggregate benefit, the estimated reimbursement is $75,000 and the employer retains $675,000 of eligible claims. A quoted factor of $625 PEPM produces the same $675,000 attachment for these 1,080 member months.
Common questions
What is an aggregate stop-loss attachment point?
The aggregate attachment point is the total amount of aggregate-eligible claims the employer retains for the covered period before aggregate stop-loss may reimburse additional eligible claims. It is usually expressed as an annual dollar amount, although carriers often calculate it from member months and a PEPM factor.
How is an aggregate corridor different from an aggregate factor?
A corridor expresses the attachment as a percentage of expected aggregate-eligible claims, such as 125%. An aggregate factor is a dollar amount per employee per month that is multiplied by member months. The two methods can produce the same attachment, but they start from different quoted inputs.
What claims count as aggregate-eligible claims?
Aggregate-eligible claims are the claims the policy says count toward the aggregate attachment and maximum benefit. The definition commonly reflects specific stop-loss reimbursements and may exclude or adjust certain claims, fees, lasers, and timing items. Use the carrier’s contract calculation rather than gross plan-paid claims when they differ.
How does changing enrollment affect the attachment point?
This calculator averages starting and ending enrollment, then multiplies that average by the covered months. More member months increase an attachment based on either expected claims PEPM or a quoted factor. A carrier using actual monthly census data can reach a different result when enrollment changes unevenly.
Are specific stop-loss reimbursements included in aggregate claims?
Often they are not counted in the same way as unreimbursed claims, but the answer depends on the aggregate policy wording and any aggregating-specific provision. This calculator expects you to enter claims already adjusted to the contract’s aggregate-eligible definition. Confirm that definition with the carrier or broker.
What do 12/12 and 12/15 contract bases mean?
A 12/12 contract generally covers claims incurred and paid during the same 12-month policy period. A 12/15 contract generally allows an additional three months for claims incurred during the policy year to be paid. The exact wording, run-out treatment, and effect on aggregate calculations come from the policy.