This talk is based on Ref. [1]. Using an Effective Field Theory approach, we obtain model independent new physics bounds from semi-leptonic τ decays. These bounds are then combined with the ones from nuclear β decay, π decays and K and hyperon decays, originally obtained in Ref. [2] and Ref. [3] respectively and updated in Ref. [1]. The interplay of the results with the so-called Cabibbo anomalies is discussed.