Materiality is a concept or convention within auditing and accounting relating to the importance/significance of an amount, transaction, or discrepancy. The objective of an audit of financial statements is to enable the auditor to express an opinion whether the financial statements are prepared, in all material respects, in conformity with an identified financial reporting framework such as Generally Accepted Accounting Principles (GAAP).
As a simple example, an expenditure of ten cents on paper is generally immaterial, and, if it were forgotten or recorded incorrectly, then no practical difference would result, even for a very small business. However, a transaction of many millions of dollars is almost always material, and if it were forgotten or recorded incorrectly, then financial managers, investors, and others would make different decisions as a result of this error than they would have had the error not been made. The assessment of what is material – where to draw the line between a transaction that is big enough to matter or small enough to be immaterial – depends upon factors such as the size of the organization's revenues and expenses, and is ultimately a matter of professional judgment.