India has to maintain tax buoyancy between 1.2 and 1.5 in order to fulfil its Viksit Bharat vision and reach a medium-term growth trajectory of 6.5-7.0, said an Ernst andamp; Young (EY), a multinational professional services firm.By definition, tax buoyancy refers to the responsiveness of tax revenue to the growth of a countrys economy. It measures how well tax revenue increases as the economy grows.