A negligent disclosure?

My self-employed client incurred an unusual and significant 'one-off' expense in the accounting period that formed the basis period for his
2005-06 tax return. As a result full details of the expense and the reasons for claiming it were given in the additional information (white space) section of the 2005-06 tax return as the nature of the expense was also a 'grey area' but with grounds for being allowable. HMRC raised an enquiry under TMA 1970 s 9A on this return and this expense item only.

Full information was again supplied to HMRC with reasons for making the claim. HMRC would not agree the claim and issued a closure notice under TMA 1970 s 28A(1) and (2) together with the appropriate appeal forms. These were completed and submitted as our client wishes to take this to a Commissioners' hearing.

It is over twelve...