Facts are established by proof and the commonest means of proof
is evidence. Evidence is that which tends to prove a fact. It is
that which would satisfy a reasonable enquirer of the fact’s
existence.
Evidence takes three forms
Over the years the Courts have developed a complex code of rules governing the nature of evidence and its admissibility. You do not need a detailed knowledge of that code in order to act as an advocate in a tax appeal. What you do need is familiarity with the basic principles. The guidelines always are that evidence
Relevant evidence is that which makes the fact more or less provable.