The Council Tax and Non-Domestic Rating (Demand Notices) (England) Regulations 1993

9.  Where a statement falls to be given as mentioned in paragraph 8 by reason of the matter referred to in sub-paragraph (a) of that paragraph—

(a) a statement of the basis on which the authority assumed that the chargeable amount for the relevant year was or should be subject to a discount of an amount equal to the appropriate percentage or twice the appropriate percentage (as the case may be); and

(b) a statement that if at any time before the end of the financial year following the relevant year the person to whom the notice is issued has reason to believe that the chargeable amount for the relevant year is not in fact subject to any discount or is subject to a discount of a smaller amount, he is required, within the period of 21 days beginning on the day on which he first had that belief, to notify the authority of it; and

(c) a statement that if the person fails without reasonable excuse to comply with a requirement contained in a statement pursuant to sub-paragraph (b), the authority may impose on him a penalty of £50.