Hi, no requirement as far as I know. I flew North Sea and the operator provided David Clark headsets (non ANR) which were dreadful especially after 5 or 6 hours flying. I ended up getting my own ANR headset and then claiming back the tax portion through HMRC, they do allow that. So not sure if you can do that ie purchase your own helmet, claim the non ANR portion through work and claim the extra tax portion back - it will still cost you but not as much