“ "tax adviser" means a firm or sole practitioner who by way of business provides advice about the tax affairs of other persons, when providing such services.”
“(4) The Commissioners [HMRC] may maintain registers of -- (a) auditors; (b) external accountants; and (c) tax advisers, who are not supervised by the Secretary of State, DETI[The Department of Enterprise, trade and Investment in Northern Ireland]or any of the professional bodies listed in schedule 3. [It was common ground that Mr Clarke was not supervised by any of these.] “(5) Where a supervisory authority [by reg 23(1)(c) this is HMRC in this case] decides to maintain a register under this regulation, it must take reasonable steps to bring its decision to the attention of those relevant persons in respect of whom the register is to be established.”
“Where a supervisory authority decides to maintain a register under regulation 32 in respect of any description of relevant persons and establishes a register for that purpose, a relevant person of that description may not carry on the business or profession in question for a period of more than six months beginning on the date on which the supervisory authority establishes the register unless he is included in the register.”