3. (1) The Board shall serve an assessment notice on every employer assessed to the levy but one notice may comprise two or more assessments.
(2) Where an election has been made, the Board may serve two or more assessment notices in respect of any establishment but—
(a)the interval between such assessment notices shall be not less than four months; and
(b)the amount of the assessment included in each such notice shall not exceed the portion of the levy which has accrued at the date of the notice, and each notice shall specify the period to which the assessment included therein relates.
(3) The amount of any assessment payable under an assessment notice shall be rounded down to the nearest £1.
(4) An assessment notice shall state the Board’s address for the service of a notice of appeal or of an application for an extension of time for appealing.
(5) An assessment notice may be served on the person assessed to the levy either by delivering it to him personally or by leaving it, or sending it to him by post, at his last known address or place of business in the United Kingdom, or, if that person is a corporation, by leaving it, or sending it by post to the corporation, at such address or place of business or at its registered or principal office.