Studying the $C\!P$ violation originating from the interference between the mixing and the decay processes of neutral $B$ mesons is an excellent instrument to investigate the presence of physics beyond the Standard Model. In this paper the most recent measurements of time-dependent $C\!P$ violation in $B^{0}_{(s)}$ decays performed by the LHCb collaboration are presented. The measurements are conducted using proton-proton collisions data recorded with the LHCb detector during the Run1 and Run2 of the LHC. The determination of the CKM phase difference $\gamma-2\beta_s$ using a sample of $B_s^0\to D_s^- K^+\pi^+\pi^-$ decays is shown, as well as the first observation of time-dependent $C\!P$ violation in the $B_s^0$ sector using a sample of $B_s^0\to K^+K^-$ decays.