Tail Coverage Window

Check a reported claim against a supplied claims-made tail period.

Description

A claims-made tail period extends a supplied reporting window beyond policy end.

A claims-made tail period extends a supplied reporting window beyond policy end. This model calculates an expiration and tests a report date against it.^[1]

Check a reported claim against a supplied claims-made tail period.

When to use Tail Coverage Window

Use this tool to check a reported claim against a supplied claims-made tail period.

Prepare the supplied policy terms, dates, assumptions or recorded indicators requested. Keep monetary amounts on one currency basis and select the applicable thresholds separately.

How to use Tail Coverage Window and understand its results

Prepare the supplied policy terms, dates, assumptions or recorded indicators requested. Keep monetary amounts on one currency basis and select the applicable thresholds separately.
Enter claimsMadePolicyEndDate, tailMonths, claimReportedDate using the field table and calculation rules, then run the tool.
Read tailExpirationDate, monthsFromPolicyEnd, withinTail. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
claimsMadePolicyEndDate	Claims-made policy end date	string	Required
tailMonths	Tail coverage duration (months)	integer; minimum: 0	Required
claimReportedDate	Claim reported date	string	Required

Enter parseable date strings, nonnegative integer months and report date no earlier than policy end. Parse UTC midnight, compute completed calendar months by comparing day numbers, and return expiration, months since end and inclusive flag.

expiration=policyEnd plus tailMonths using setUTCMonth; within=reported≤expiration

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
tailExpirationDate	Tail expiration date	string
monthsFromPolicyEnd	Whole months from policy end	integer; minimum: 0
withinTail	Claim reported within tail	boolean

json

{
  "input": {
    "claimsMadePolicyEndDate": "2025-01-01",
    "tailMonths": 12,
    "claimReportedDate": "2025-07-01"
  },
  "output": {
    "tailExpirationDate": "2026-01-01",
    "monthsFromPolicyEnd": 6,
    "withinTail": true
  }
}

Limitations and assumptions

Native date parsing can normalize dates; adding months can overflow short months rather than clamp to month end. No occurrence date, retroactive date or policy coverage is checked.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Extremely large text inputs are rejected. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Filing Expiration: Calculate a financial-responsibility filing expiration from a supplied duration. For a complementary task, use Contestability Window: Check an event date against a caller-supplied contestability window.

References

Tail Coverage Window — tool.io

Similar or alternative tools

Filing Expiration
Calculate a financial-responsibility filing expiration from a supplied duration.
Contestability Window
Check an event date against a caller-supplied contestability window.