Since the beginning of the WLCG Project the Spanish ATLAS computer centres have contributed with reliable and stable resources as well as personnel for the ATLAS Collaboration.
Our contribution to the ATLAS Tier2s and Tier1s computing resources (disk and CPUs) in the last 10 years has been around 5%, even though the Spanish contribution to the ATLAS detector construction as well as the number of authors are both close to 3%. In 2015 an international advisory committee recommended to revise our contribution according to the participation in the ATLAS experiment. With this scenario, we are optimising the federation of three sites located in Barcelona, Madrid and Valencia, taking into account that the ATLAS collaboration has developed workflows and tools to flexibly use all the resources available to the collaboration, enlarging the original statically-tiered structure of WLCG with a more dynamic structure nucleated around highly reliable centers with sufficient disk storage resources.
In this contribution, we would like to show the evolution and technical updates in the ATLAS Spanish Federated Tier2 and Tier1. Some developments we are involved in, like the Event Index and Event WitheBoard projects, as well as the use of opportunistic resources will be useful to reach our goal. We discuss the foreseen/proposed scenario towards a sustainable computing environment for the Spanish ATLAS community in the Run3 and HL-LHC period.