I also got the same letter from HMRC this morning saying their records show that I represent one or more clients HMRC are investigating because their records show they (the clients) have used a tax avoidance scheme. I am sure (or as sure as I can be) that I have no clients who have used a tax avoidance scheme or who are under investigation for using a scheme. If this is a circular it is very badly phrased!
My answers
I also got the same letter from HMRC this morning saying their records show that I represent one or more clients HMRC are investigating because their records show they (the clients) have used a tax avoidance scheme. I am sure (or as sure as I can be) that I have no clients who have used a tax avoidance scheme or who are under investigation for using a scheme. If this is a circular it is very badly phrased!