If you have not already done so, you should also think of the
likelihood of relevant information being available from other
sources. There could be information held elsewhere in the HMRC or
available from outside sources. The HMRC obtains a great deal of
information by use of its third party information powers (see the
TPI Directory). There is also much information available on the
Internet.
If you have an appeal from a company director against the
amendment of his self-assessment there might, for example, be very
relevant information in the Directors' reports attached to the
company's accounts held by the office dealing with the company's
affairs. Similarly, where an employee is claiming a deduction for
expenses in his self-assessment, the employer will have important
information about the scope of the employee's duties.
And the papers for the purchaser of land may give a very
different picture of the transaction from that put forward by the
vendor whose profit on disposal is being assessed. Those papers
might show that an interview with the purchaser would be
worthwhile. This is not to suggest that the files for other parties
should invariably be consulted as part of the preparation for a
contested appeal, but you should at least consider looking at
them.