Status and future evolution of the ATLAS Offline Software

These proceedings give a summary of the many software upgrade projects undertaken to prepare ATLAS for the challenges of LHC Run-2. Those projects resulted in the reduction of the CPU time required for reconstruction of real data with an average $mu$ of 40 by more than 3 compared to 2012, which was required to meet the challenges of the expected increase in pileup and the higher data taking rate of up to 1 kHz. By far the most ambitious project was the implementation of a completely new Analysis Model, based on a new ROOT readable reconstruction format, xAOD, a reduction framework based on a train model to centrally produce skimmed data samples and an analysis framework. These proceedings close with a brief overview of future software projects and plans that will lead up to the coming Long Shutdown 2 as the next major ATLAS software upgrade phase.