Advances in experimental physics, specifically light sources emitting at an attosecond time scale, has enabled the time resolution of atomic processes like photoionization. Recent developments have allowed these sources to produce light with non-linear polarization. There exists various theoretical methods that can simulate experimental set-ups that make use of these attosecond sources. The aim of this thesis project was to extend two of these methods to be able to simulate circularly polarized light in order to both better model experimental results and come up with new potentially interesting experiments. This has resulted in an extended version of the Random Phase Approximation with Exchange method capable of simulating an ionization process by light of arbitrary polarization, as well as well as an extended version of the NewStock package that is capable of time-resolved simulation of matter interactions with arbitrary light pulses.