Nonreciprocity in time-modulated metasurfaces is normally achieved only when it is combined with with space modulation, using at least two time-varying elements located at different positions in space. In this talk, we present the idea of time-modulated bianisotropic metasurfaces where nonreciprocal wave propagation is realized with time modulation of only a single element. The results show that by uniformly modulating a capacitive sheet mounted on a sub-wavelength dielectric layer, one can obtain strong nonreciprocity and achieve unidirectional wave amplification.