The observed excess in $\bar B\to D^{(*)}\tau\bar\nu$ is one of the major anomalies in particle physics. After a short summary of experimental results and standard model predictions, we introduce a model-independent approach using an effective field theory in order to identify possible new physics scenarios. The allowed regions of Wilson coefficients are obtained with the most recent experimental data. We also discuss other observables, $q^2$ distributions and a tau polarization. We briefly mention future prospects of experiments.