For the purpose of instituting some penalty proceedings the time limit begins to run from the date when the relevant liability is finally determined. Where, therefore, in an enquiry case there are open appeals, take care to ensure that mere agreement of figures incidental to the ascertainment of the duty underpaid cannot be represented as a final determination of liability for the purposes of TMA70/S54. In such a case, if you issue a letter including a computation of income or duty for the taxpayer's agreement, or a letter agreeing a computation put in by or on behalf of the taxpayer, you must clearly state that agreement of the computation is not to be binding for the purposes of TMA70/S54. If, exceptionally, it is the your intention that the agreement shall be so binding you must state in the letter that the TMA70/S54 is to apply.
