Why Filing Scope Must Be Explicit
A rate filing is easier to review when its boundaries are unambiguous. The reader should be able to tell which business is affected, what is changing, when the change applies, and what action is being requested. A statement such as “revise rates for the product” may not answer whether the proposal includes every territory, only renewals, a new coverage option, or a change to how risks are classified.
Scope is not the same as the actuarial support for a proposed change. It identifies the business and actions addressed; the analysis supporting the indicated change is developed separately. The exact filing categories and required forms vary by jurisdiction, so the scope description must be consistent with the applicable filing requirements. This tutorial is aligned with the CAS Exam 8 (Advanced Ratemaking) syllabus.
Separate the Business Boundary From the Proposed Action
A useful scope description has two parts. First, define the affected business: for example, the jurisdiction, line, product or program, policy status, and any relevant coverage or eligibility boundary. Second, identify the proposed action: what is requested to change and what is intended to remain unchanged. A filing can address one or several kinds of action, but they should not be blurred together.
The following distinctions are central to describing the action accurately:
| Type of action | What changes | Scope question to answer |
|---|---|---|
| Rate-level change | A common multiplicative adjustment to otherwise unchanged premiums or rates | Which in-scope policies receive the adjustment? |
| Rating-rule change | A rule governing how a risk is rated, such as a calculation or eligibility rule | Which risks or transactions are governed by the revised rule? |
| Classification change | How a risk is assigned to a class or rating group | Which risks may move between classes, and under what definition? |
| Rating-factor change | A factor or relativity applied to a rating characteristic | Which factor values or combinations are revised? |
| Coverage change | The insurance protection, limit, option, or policy provision offered | Which policyholders gain, lose, or may select the changed coverage? |
These categories can overlap. A proposal might request a common rate-level adjustment and a change to a rating factor. It might also revise an eligibility rule that determines which risks may purchase an optional coverage. The filing scope should name each action rather than describing all of them as a “rate change.” Whether a particular action requires a specific filing treatment depends on the jurisdiction.
A Simple Rating Representation Clarifies the Distinction
Suppose, for illustration, a premium is calculated as a base amount multiplied by rating factors. Let \(P_0\) be the current premium, \(B\) the base amount, and \(f(z)\) the combined factor for a risk with characteristics \(z\). Assume the proposed rate-level change is a common multiplier \(k\), while the rating rules and characteristics remain unchanged.
Under those assumptions, dividing the proposed premium by the current premium gives:
The common factor \(k\) is why this is a rate-level change: every otherwise comparable in-scope risk receives the same proportional adjustment. The conclusion depends on the stated assumptions—particularly that the rating structure and the in-scope risk characteristics have not changed.
If the factor function also changes from \(f_0(z)\) to \(f_1(z)\), the premium ratio becomes:
Now the impact can differ by risk because the factor ratio may vary with \(z\). This is not adequately described as a common rate-level change alone. If a filing contains both actions, it should identify both: the common adjustment and the particular factor or rule revisions.
Worked Example: Identifying a Pure Rate-Level Change
A hypothetical insurer proposes a 6% increase for all renewal policies in one specified jurisdiction and personal auto program. Rating variables, classifications, coverages, and rating rules are unchanged. An in-scope policy currently has a premium of $1,250. Determine the proposed premium and classify the action.
Method. Because the proposal changes only the common rate level, apply the multiplier \(k=1.06\) to the current premium.
Step 1: Calculate the change. The increase is \(0.06 \times \$1{,}250 = \$75\).
Step 2: Calculate the proposed premium. The premium is \(\$1{,}250 + \$75 = \$1{,}325\), equivalently \(\$1{,}250 \times 1.06 = \$1{,}325\).
Step 3: Check the percentage. The ratio is \(\$1{,}325/\$1{,}250=1.06\), so the increase is exactly 6%. The result is $1,325.00.
Scope conclusion. This is a rate-level action for the defined renewal business, not a classification, factor, or coverage change. The common mistake is to call any premium change a rate-level change; here that description is justified only because the rating structure and coverage are explicitly unchanged.
State the Affected Business and the Effective-Date Boundary
A complete boundary generally identifies the relevant jurisdiction and line, then narrows the business further if the proposal is limited to a product, program, coverage, policy status, or other defined segment. It should also say what is excluded when an omission could create a reasonable ambiguity. For example, “renewal policies only” is clearer than “existing business” if new business is not included.
Effective dates require equally careful wording. State the date or period on which the change begins and the transaction that determines applicability. That transaction might be a policy’s effective date, renewal effective date, or another date defined by the applicable rules. Do not assume that a filing’s submission or approval date alone tells the reader which policies receive the proposed terms. The governing jurisdiction’s requirements control.
Identify the jurisdiction, line, product or program, and any relevant segment or coverage.
State whether the action applies to new business, renewals, in-force policies, or a precisely defined subset.
Give the date and identify which policy or transaction date determines applicability.
Separate rate-level, rule, classification, factor, and coverage changes, and state what remains outside the request.
Apply the description to representative policies on both sides of each date, jurisdiction, product, or coverage boundary.
Worked Example: Separating a Factor Revision From a Rate-Level Change
A hypothetical filing covers renewal policies in a specified small-business program and jurisdiction. It requests both a 4% common increase and a revision to one vehicle-use factor from 1.10 to 1.25. For a policy with base amount $500 and unchanged territory factor 1.20, calculate the current and proposed premiums, and describe the actions.
Method. Calculate the current premium using the current factors. For the proposal, first replace the specified factor, then apply the common multiplier \(1.04\). Assume all other inputs and rules remain unchanged.
Step 1: Calculate the current premium. The combined current factors are \(1.20 \times 1.10 = 1.32\). Thus, the current premium is \(\$500 \times 1.32 = \$660\).
Step 2: Calculate the premium after the factor revision but before the common increase. The revised combined factors are \(1.20 \times 1.25 = 1.50\). The premium is \(\$500 \times 1.50 = \$750\).
Step 3: Apply the rate-level multiplier. The proposed premium is \(\$750 \times 1.04 = \$780\). The common adjustment adds \(\$750 \times 0.04 = \$30\) to the post-factor premium.
Step 4: Check the total impact against the original premium. The increase is \(\$780-\$660=\$120\), and the proportional change is \(\$120/\$660=0.181818\ldots\), or approximately 18.18%. The new premium is $780.00.
Scope conclusion. The request contains two actions: a 4% rate-level change and a vehicle-use factor revision. It is not accurate to describe the result for this policy as a 4% increase overall. A common mistake is to add the 4% directly to the 13.64% factor-driven increase; the correct calculation compounds the multipliers: \((1.25/1.10)\times1.04 \approx 1.1818\).
Coverage Changes and Classification Boundaries
A coverage change changes what protection is available or provided; it is not merely a different price for identical protection. Examples include adding an optional endorsement, changing a limit option, or revising a covered event. The scope should identify the affected coverage and whether the proposal makes it available to new policies, renewals, or both. It should also distinguish a coverage revision from a rate change that applies to an unchanged coverage.
Classification and rating-rule changes also need precise definitions. If a revised rule changes which class a risk enters, describe the relevant boundary in operational terms. If the filing changes a factor but not the rule assigning risks to factor values, say so. Conversely, a new assignment rule is a structural change even if the numerical factor table stays the same. A useful scope test is: could two otherwise similar risks receive different treatment because the definition, rule, or coverage changed? If yes, identify the structural action separately from any common rate adjustment.
Worked Example: Applying Coverage and Date Boundaries
A hypothetical insurer proposes a new optional equipment endorsement for a commercial property program in one jurisdiction. It would be available only for policies with effective dates on or after July 1, 2027, and only at renewal; new business is excluded from this request. The associated premium for an eligible policy would be $180. Determine whether each case is within the proposed scope and calculate the added premium when applicable.
Method. Test each case against all three stated conditions: correct jurisdiction and program, renewal transaction, and policy effective date on or after July 1, 2027. The endorsement is optional, so its stated premium is added only when selected.
Case A. A renewal in the named jurisdiction and program has a July 1, 2027 effective date and selects the endorsement. The date boundary is inclusive (“on or after”), so the policy is eligible. Added premium is $180.00.
Case B. A renewal in the same jurisdiction and program has a June 30, 2027 effective date. It fails the effective-date condition, so the proposed endorsement terms do not apply; added premium under this proposal is $0.00.
Case C. A new policy has an August 1, 2027 effective date and selects the endorsement. It meets the date condition but fails the renewal-only condition, so it is outside this request; added premium under this proposal is $0.00.
Check. Only Case A satisfies every scope condition. The common mistake is to treat the date as the only test, thereby including Case C. The proposed action is a coverage availability and premium change limited to the stated renewal business, not a general rate-level change for the whole program.
Common Scope Errors
- Using “rates” as a catch-all. A factor revision, class reassignment, or coverage change may alter premium, but it is not automatically a uniform rate-level change.
- Leaving the policy transaction unclear. “Effective July 1” does not by itself say whether applicability follows a policy effective date, renewal date, or another defined transaction date.
- Defining the product too broadly. A line name may include multiple programs, coverages, or policy groups. Name narrower boundaries when they matter.
- Omitting exclusions. If new business, a jurisdiction, or a coverage is excluded, state that directly when a reader could otherwise reasonably include it.
- Combining actions without separating them. When a proposal contains both a common multiplier and structural changes, list each action so its affected risks can be understood.
Check Your Understanding
For each problem, identify the scope or calculate the requested result using only the stated conditions.
- A hypothetical filing requests a 3% common increase for renewals in one named jurisdiction and program. A policy has a current premium of $900, and no rating or coverage terms change. What is its proposed premium, and what type of action is requested? (Answer: $927.00; a 3% rate-level change for the defined renewal business.)
- A policy has base premium $400 and a current factor of 1.15. The proposal changes that factor to 1.25, with all other terms unchanged. What is the current premium, proposed premium, and percentage change? (Answer: $460.00; $500.00; an increase of approximately 8.70%, caused by a factor change rather than a common rate-level change.)
- A proposed endorsement applies only to renewals with effective dates on or after October 1, 2027. A renewal effective October 1 selects it; a new policy effective October 15 selects it. Which transaction is within scope? (Answer: The October 1 renewal only; the new policy is excluded by the renewal-only condition.)
- A filing proposes a 5% common multiplier and changes a class factor from 0.90 to 1.08. For an otherwise unchanged policy with current premium $1,000, what is the proposed premium if the factor change is applied first and the common multiplier second? (Answer: $1,260.00; the factor ratio is 1.08/0.90 = 1.20, and \(1{,}000 \times 1.20 \times 1.05 = 1{,}260\).)
- A filing applies to renewals in Program A in Jurisdiction X with effective dates from January 1 through March 31, 2028, inclusive. A Program A renewal in Jurisdiction X has an effective date of April 1, 2028. Does it meet the stated scope? (Answer: No; April 1 is after the inclusive end date of March 31.)