What term describes other insurance written on the same risk, but not on the same coverage basis?

The correct term for insurance written on the same risk but not on the same coverage basis is nonconcurrency. Nonconcurrency occurs when multiple insurance policies are issued for the same risk, but their coverage terms and conditions do not align completely. This can lead to potential gaps in protection or conflicting coverage requirements, as each policy may impose different limitations, exclusions, or coverage conditions.

Understanding nonconcurrency is essential for both insurers and insureds because it can impact claim handling and risk management. When policies are nonconcurrent, the insured must carefully navigate how coverage applies in the event of a loss, as the terms of each policy may not work harmoniously together.

In contrast, other terms provided represent different aspects of insurance coverage. For instance, primary and excess refer to the hierarchy of coverage that dictates which policy responds first in the event of a claim. Pro rata refers to the distribution of losses among multiple insurers based on their respective share of the total insured amount. Contribution by equal shares involves multiple insurers paying an equal portion of a loss until it is fully covered. Each of these terms describes specific arrangements or methods of dealing with insurance claims and coverage, but they do not capture the specific scenario of overlapping coverage with differing terms that nonconcurrency addresses.