Timeliness principle in accounting refers to the need for accounting information to be presented to the users in time to fulfill their decision making needs.
Timeliness of accounting information is highly desirable since information that is presented timely is generally more relevant to users while conversely, delay in provision of information tends to render it less relevant to the decision making needs of the users. Timeliness principle is therefore closely related to the relevance principle.
Timeliness is important to protect the users of accounting information from basing their decisions on outdated information. Imagine the problem that could arise if a company was to issue its financial statements to the public after 12 months of the accounting period. The users of the financial statements, such as potential investors, would probably find it hard to assess whether the present financial circumstances of the company have changed drastically from those reflected in the financial statements.