Oliver has a practice encompassing all areas of tax law, contentious and non-contentious.

In July 2021, the Chambers HNW guide wrote:
“Oliver Marre is “our go-to when we need advice,” reveals an instructing solicitor, adding: “He’s extremely approachable, knowledgeable and brilliant with clients.  Marre often advises high net worth clients on a range of tax matters.  Another interviewee enthuses: “What sets him apart, I think, is his ability to relate to clients and explain difficult concepts or strategic points to them.  I am always confident in recommending him to clients and colleagues.”

Oliver is also listed in the other main legal directories.

As well as his broad general revenue advisory work and litigation, Oliver provides tax advice in the contexts of trusts disputes, mediations, in cases before the Family Division (including complex or HNW divorce cases) and in relation to the taxation of charities and charitable donors.