UAu2Si2 belongs to the most puzzling members of the UT2Si2 (T = transition metal) family of compounds. Recently we have mastered the technology of growth of high-quality UAu2Si2 single crystals and investigated their physical properties in detail. It exhibits weak ferromagnetic c-axis component below 50 K and second magnetic antiferromagnetic-like phase transition at 20 K. They both show large anisotropy. Our previous Si-NMR and neutron diffraction experiments found the propagation vector of (2/3,0,0) and moments aligned along the c-axis in the squared-up (++-) ground state structure. High field studies applied along the c-axis up to 58 T revealed presence of metamagnetic transition in 22 T at 1.8 K. Together with magnetization and magnetostriction results it helps to construct the magnetic phase diagram of the compound. Our proposed neutron diffraction study on HFM/EXED is focused on determination of magnetic structure at higher magnetic fields close and above metamagnetic transition.