Electromagnetic computations, where the wavelength is small in relation to the geometry of interest, become computationally demanding. In order to manage computations for realistic problems like electromagnetic scattering from aircraft, the use of parallel computing is essential. In this paper, we describe how a solver based on a hierarchical nested equivalent source approximation can be implemented in parallel using a task based programming model. We show that the effort for moving from the serial implementation to a parallel implementation is modest due to the task based programming paradigm, and that the performance achieved on a multicore system is excellent provided that the task size, depending on the method parameters, is large enough.