  In this proceedings we briefly report on the state-of-the-art NLO QCD
computation for the $pp\to t\bar{t}\gamma$ process in the di-lepton channel. We
describe higher-order corrections to the $e^+\nu_e \, \mu^- \bar{\nu}_\mu \,
b\bar{b}\gamma$ final state at the LHC with $\sqrt{s}=13$ TeV. Off-shell top
quarks, double-, single- as well as non-resonant top-quark contributions along
with all interference effects are consistently incorporated at the matrix
element level. Results are presented in the form of fiducial integrated and
differential cross sections. The impact of top quark modelling is scrutinised
by an explicit comparison with the results in the narrow-width approximation.
Both types of predictions are now available in the HELAC-NLO framework.
