SUSY searches at $\sqrt{s}$ = 13 TeV with two same-sign leptons or three leptons, jets and $E_T^{miss}$ at the ATLAS detector - Background estimation and latest analysis results.

This proceeding summarizes a search for supersymmetric phenomena in final states with two leptons (electrons or muons) of the same electric charge or three leptons, jets and missing transverse energy. While the same-sign or three leptons signature is present in many SUSY scenarios, SM processes leading to such events have very small cross-sections. Therefore, this analysis benefits from a small SM background in the signal regions leading to a good sensitivity especially in SUSY scenarios with compressed mass spectra or in which the R-parity is not conserved. The search was performed with the full dataset recorded with the ATLAS detector during the year 2015 and 2016 corresponding to a total integrated luminosity of 36.1 fb$^{-1}$. No significant excess above the Standard Model expectations is observed. The results are interpreted in several simplified supersymmetric models featuring R-parity conservation or R-parity violation, extending the exclusion limits from previous searches.