W+jets backgrounds in charged Higgs searches with the ATLAS experiment at the LHC

W+jets events with one lepton in the final state could be an important background for charged Higgs boson searches. In the H+ -> tau nu channel for instance, W + jets will contribute to the backgrounds where a light jet fakes a hadronic tau jet. Below the top quark mass, where the H+ -> tau nu will appear as an excess of tau leptons compared to electrons or muons from SM model expectation, the understanding of fake tau from background sources including W+jets will be essential to establish the existence of a viable signal. Data driven method for the measurement of W+jets background are needed. In this talk, we will describe the available methods to estimate this background from data and its relevance to charged Higgs searches.