Combined kinematic and cosmological redshift ($1+z_{\mathrm{tot}}=(1+z_{\mathrm{cosm}})(1+z_{\mathrm{kin}})$)

Frequency ratios multiply when a photon is transformed first between a source and its local comoving frame, then propagated through an expanding universe. Thus the kinematic redshift and cosmological redshift factors multiply. Their redshifts themselves add only to first order when both are small.