Mapping Insurance Transactions to Experience Periods

Why One Transaction Can Have Several Period Labels

Insurance records contain several dates for the same policy or claim. A policy may begin in one calendar year and end in the next; a covered loss may occur near the end of the policy term, be reported later, and be paid later still. The period assigned to a record depends on the purpose of the grouping. A date that answers one period question does not automatically answer another.

This tutorial focuses on period mapping: identifying the date that governs a label and applying the stated convention consistently. It does not determine when a premium or claim cost should be recognized, or how an amount should be recorded. Those are accounting questions; here, the accounting date is supplied as part of the transaction data. The distinctions are aligned with the CAS Exam 5 (Basic Ratemaking and Estimated Claim Liabilities) syllabus.

Definitions: An accounting period is the period containing the date on which a specified transaction or accounting entry is recorded under the stated convention. A policy period is the coverage interval shown by the policy’s effective and expiration dates. A policy-year grouping commonly assigns a policy to the year in which its coverage begins. An underwriting-year grouping assigns business to a year based on the designated underwriting or policy-inception date. An accident period is determined by when the loss event occurred. A report period is determined by when the insurer received or recorded the claim report, as defined for the data. A payment period is determined by when the claim payment was made.

Period labels must be read with their conventions. For example, a company might use calendar years for accident-year grouping, while another analysis could use fiscal periods. In the examples below, periods are calendar years, and the dates and rules needed for classification are explicitly supplied. Policy period means the actual coverage interval; policy year and underwriting year are year-based groupings. Where the examples use the policy’s inception date as the underwriting date, that convention is stated rather than assumed to apply to every data system.

A Date-to-Period Mapping Rule

For a year-based grouping, the basic operation is to select the date relevant to that grouping and locate the calendar year containing it. The relevant date is not necessarily the date that appears first in a record, nor the date closest to the accounting cutoff.

\begin{aligned} \text{Accounting year} &\longleftarrow \text{specified accounting or transaction date},\\ \text{Policy year} &\longleftarrow \text{policy inception date},\\ \text{Underwriting year} &\longleftarrow \text{designated underwriting date},\\ \text{Accident year} &\longleftarrow \text{date of loss occurrence},\\ \text{Report year} &\longleftarrow \text{claim report date},\\ \text{Payment year} &\longleftarrow \text{claim payment date}. \end{aligned}

The policy period itself is an interval, not a single year label. If a policy is effective from July 1, 2024 through June 30, 2025, a loss on December 30, 2024 falls within that interval. The policy’s policy-year grouping can still be 2024, even though part of its coverage falls in 2025.

Identify the item being classified.
Is the row a premium transaction, a claim report, a claim recognition entry, or a payment? A policy and a transaction related to that policy need not have the same accounting date.

Choose the requested period label.
Do not begin with a date and guess its purpose. First decide whether the question asks for an accounting, policy, underwriting, accident, report, or payment period.

Use the date relevant to that label.
For a claim, keep occurrence, report, accounting, and payment dates as separate fields. For a policy, use its coverage dates and the stated convention for any year grouping.

Check the result against the timeline.
Confirm that a date just before year-end has not been assigned to the year of a later report, payment, or posting.

Worked Mapping Examples

Worked Example: A Policy and Claim Crossing Year-End

A hypothetical commercial policy is accepted on November 20, 2024 and provides coverage from December 1, 2024 through November 30, 2025. Use the acceptance date as the underwriting date and the inception year as the policy-year convention. A premium transaction is recorded on December 3, 2024. A covered loss occurs on December 30, 2024, is reported on January 4, 2025, and has a specified claim recognition entry recorded on January 10, 2025. The claim is paid on February 20, 2025. Assign each applicable period.

Step 1: Determine the policy interval. The coverage begins December 1, 2024 and ends November 30, 2025. Thus, the policy period crosses two calendar years; it is not itself a single calendar year.

Step 2: Assign the policy and underwriting years. The policy inception date is December 1, 2024, so the policy-year grouping is 2024. Under the stated convention, the underwriting date is November 20, 2024, so the underwriting-year grouping is also 2024.

Step 3: Classify the premium transaction. Its specified accounting date is December 3, 2024, so its accounting year is 2024. It is associated with the policy whose policy-year and underwriting-year groupings are both 2024. Accident, report, and payment years do not apply to this premium transaction.

Step 4: Classify the claim by event and reporting dates. The loss occurred December 30, 2024, inside the policy interval, so the applicable policy period is December 1, 2024–November 30, 2025, the policy year is 2024, and the accident year is 2024. The report date is January 4, 2025, so the report year is 2025.

Step 5: Keep the remaining transaction dates distinct. The stated recognition entry date, January 10, 2025, gives that entry an accounting year of 2025. The payment date, February 20, 2025, gives the payment year of 2025. The result is therefore accident year 2024, report year 2025, accounting year 2025 for the specified entry, and payment year 2025.

Check. The loss date lies within the stated coverage interval, and every year label follows its own specified date. Common mistake avoided: assigning the claim to accident year 2025 because it was reported or entered in 2025. Those dates determine report and accounting periods, not the accident period.

Worked Example: Separating a Claim’s Four Dates

A hypothetical vehicle policy runs from August 15, 2023 through August 14, 2024. For this example, policy year and underwriting year are both based on the 2023 inception date. A collision occurs on August 14, 2024. The insurer receives the report on September 2, 2024. A claim entry specified in the data is recorded on December 31, 2024, and a payment is issued on January 6, 2025. Map the policy, underwriting, accident, report, accounting, and payment periods.

Policy and underwriting groupings. The policy begins August 15, 2023, so its policy-year grouping is 2023. The given underwriting convention also uses that inception date, so its underwriting year is 2023. Its full policy period is August 15, 2023–August 14, 2024.

Accident period. The collision date, August 14, 2024, is the final day of the stated policy period. The accident year is 2024, and the occurrence falls within the coverage interval.

Report period. The report was received September 2, 2024, so the report year is 2024. This happens to match the accident year, but it is determined from a different date.

Accounting period. The specified claim entry was recorded on December 31, 2024. Therefore, that entry belongs to accounting year 2024.

Payment period. The payment date is January 6, 2025, so the payment year is 2025.

Check. The five year-based labels are policy 2023, underwriting 2023, accident 2024, report 2024, accounting 2024 for the specified entry, and payment 2025. Common mistake avoided: moving the payment into accounting year 2024 because the claim entry was recorded then. The payment date, rather than the entry date, governs payment year.

Worked Example: Mapping Several Records in a Data Extract

A hypothetical insurer prepares a calendar-year mapping for two policies. Policy A has an underwriting date of December 28, 2024 and covers January 1 through December 31, 2025. Its premium transaction is recorded on January 3, 2025. A loss under A occurs on December 31, 2025, is reported on January 2, 2026, and is paid on March 15, 2026. Policy B has an underwriting date of December 30, 2025 and covers February 1, 2026 through January 31, 2027. Its premium transaction is recorded on December 30, 2025. For both policies, use underwriting year from the supplied underwriting date and policy year from the coverage inception date. Map each item.

Policy A. Its coverage starts January 1, 2025 and ends December 31, 2025. The policy year is 2025. Its underwriting date is December 28, 2024, so its underwriting year is 2024. The premium transaction accounting date is January 3, 2025, giving it accounting year 2025.

Policy A claim. The loss date, December 31, 2025, falls on the final day of the coverage interval, so the claim is in policy year 2025 and accident year 2025. The January 2, 2026 report gives report year 2026. The March 15, 2026 payment gives payment year 2026. No accounting year for a claim entry is supplied, so one cannot assign that separate label from these facts.

Policy B. Its coverage interval is February 1, 2026 through January 31, 2027. The inception-date convention gives policy year 2026; the supplied underwriting date gives underwriting year 2025. The premium transaction was recorded December 30, 2025, so its accounting year is 2025.

Check. Policy A demonstrates that an underwriting year can precede its policy year under the dates supplied. Policy B demonstrates that its premium transaction’s accounting year can precede the coverage’s policy year. Do not infer missing claim dates or an accounting period from a premium or policy date. Common mistake avoided: assigning every row associated with Policy B to 2026. Its accounting date is in 2025, while its policy inception is in 2026.

Why the Date Rule Works

A period label is a classification of a record for a particular purpose. The definition of each grouping specifies what event the label describes. Accounting year locates a specified accounting date; accident year locates the occurrence; report year locates the report; payment year locates the payment. Consequently, changing one date can change one label without changing the others.

For example, if a claim is reported later but its occurrence date stays fixed, its report year may change while its accident year does not. If a payment is delayed, the payment year may change without changing the occurrence year. This independence is why period mapping should be done date by date rather than by copying one year field across the entire record.

Key takeaway: Assign each period from its own governing date. Preserve the actual policy interval, use only the stated convention for policy and underwriting year, and do not substitute a report, payment, or accounting date for the loss occurrence date.

Common Mapping Errors

Using a later claim date for accident year. A report or payment in a later year does not move the accident into that year.
Treating a policy period as a calendar-year label. A policy may cover parts of two calendar years; record its start and end dates, then apply the requested year convention.
Assuming policy year and underwriting year must always match. Their dates may coincide under a particular convention, but the mapping must follow the dates specified for each.
Using the transaction’s accounting date for every purpose. That date can identify its accounting period, but it does not replace the policy inception, loss, report, or payment date.
Filling in an unstated date. If a record has no specified accounting-entry date, its accounting period cannot be inferred merely from its payment date or from the year of the associated policy.
Ignoring the cutoff convention. Use the date defined by the data or accounting procedure. A receipt date, posting date, and recognition date need not be interchangeable.

Check Your Understanding

For each problem, identify the requested period labels from the dates given. Treat all year groupings as calendar years.

A policy begins October 1, 2024 and expires September 30, 2025. Its policy-year convention is inception year. A loss occurs September 30, 2025 and is reported October 3, 2025. What are the policy period, policy year, accident year, and report year? (Answer: October 1, 2024–September 30, 2025; policy year 2024; accident year 2025; report year 2025.)
A claim occurs December 29, 2023, is reported January 4, 2024, and is paid December 20, 2024. What are its accident, report, and payment years? (Answer: accident year 2023; report year 2024; payment year 2024.)
A policy’s supplied underwriting date is December 31, 2025; coverage begins January 1, 2026. A premium transaction is recorded December 30, 2025. Use inception year for policy year. Give the underwriting, policy, and accounting years for the premium transaction. (Answer: underwriting year 2025; policy year 2026; accounting year 2025.)
A covered loss occurs March 8, 2024, is reported March 12, 2024, has a specified claim entry recorded on December 31, 2024, and is paid January 2, 2025. Give the accident, report, accounting, and payment years. (Answer: accident year 2024; report year 2024; accounting year 2024; payment year 2025.)
A policy covers November 1, 2024 through October 31, 2025, and its underwriting date is October 25, 2024. A loss occurs November 1, 2024, is reported November 2, 2025, and is paid February 1, 2026. Using inception year for policy year, identify the policy period and the policy, underwriting, accident, report, and payment years. (Answer: policy period November 1, 2024–October 31, 2025; policy year 2024; underwriting year 2024; accident year 2024; report year 2025; payment year 2026.)

What You'll Learn