Underwriting result based on written premiums and ultimate losses from loss events falling within the same accounting period, where the accounting period is the period covered by the insurance policy or reinsurance agreement, regardless of when the premiums and losses are actually reported, booked or paid.
For example, the 2019 underwriting Year includes results in calendar Year 2019 and all future calendar Years on business bound in 2019.
Compare with Accident Year of Experience and Calendar Year of Experience.