Measurements of cross sections for the production of Higgs bosons decaying to tau lepton pairs performed by the ATLAS experiment, using LHC proton-proton collision data from 2015 and 2016 at a centre of mass energy of 13 TeV, are presented. All measured values are consistent with their Standard Model (SM) predictions. Additionally it is possible to probe CP properties with these event signatures. A search for CP violation in the production vertex of the Higgs boson via vector boson fusion production at 8 TeV finds no deviations from the SM and sets limits on a CP-mixing parameter in the $HVV$ vertex at 68% confidence level (CL). The High Luminosity LHC will allow the CP-mixing in the Higgs boson decay to tau leptons pairs to be probed, and to set limits at 95% CL.