Methods and apparatus for dynamic modification of interruptibility settings of network-accessible resources are disclosed. A system includes a resource manager and a plurality of resource instances, each of which has an interruptibility setting. In response to an instance acquisition request, the resource manager allocates an instance with a first interruptibility setting, allowing the resource manager to revoke the client's access to the instance without a notification. In response to an approval of an interruptibility upgrade request, the resource manager modifies the interruptibility setting to a second setting that allows the client to retain access to the instance for at least a specified time. Respective billing amounts for the client's use of the instance are determined for each of the interruptibility settings used.