An occurrence-based insurance policy protects you from claims resulting from any incident that occurred during the policy period, regardless of when the claim was filed. It’s permanent coverage for a certain time period, so long as the incident falls within the terms of your policy.
On the other hand, a claims-made policy provides coverage for claims only if both the incident and the claim occur during the policy period. If you renew the same policy year after year, claims are accepted as far back as your retroactive date, which is also known as a prior acts date.