Expected performance of the ATLAS $b$-tagging algorithms in Run-2

The expected performance of the ATLAS $b$-tagging algorithms for Run-2 is presented. Significant improvements with respect to Run-1 are achieved due to the addition of the Insertable B-Layer, which results in an extra pixel layer closer to the beampipe, and due to several enhancements to the tracking and $b$-tagging algorithms. The new default multivariate $b$-tagging algorithm for Run-2 is described and a detailed set of performance plots is presented.