  We discuss the combined effect of QED and QCD corrections to the evolution of
parton distributions. We extend the available knowledge of the Altarelli-Parisi
splitting functions to one order higher in QED, and provide explicit
expressions for the splitting kernels up to ${\cal O}(\alpha \,
\alpha_{\mathrm{S}})$. The results presented in this article allow to perform a
parton distribution function analysis reaching full NLO QCD-QED combined
precision.
