Abstract: Embodiments of the present invention are directed to dynamically allocating shared cloud-based resources among multiple parties. A cloud provider provides a quota service that implements two quota allocation models: a reserved model and a hybrid model. The reserved model allows for reserved quota allocations, and the hybrid model allows for both reserved and fair use quota allocations. Quota trees are used to track resource usage and to ensure usage remains within specified quota limits. While the cloud provider is able to efficiently manage its resources, an organization that uses the cloud provider's resources does not need to purchase as many resources, such as space, bandwidth, memory usage, processing power, or other unit of work.