Comparability is one of the key qualities which accounting information must possess. Accounting information is comparable when accounting standards and policies are applied consistently from one period to another and from one region to another. The characteristic of comparability of financial statements is important because it allows us to compare a set of financial statements with those of prior periods and those of other companies.
The concept of consistency means that accounting methods once adopted must be applied consistently in future. Also same methods and techniques must be used for similar situations.
It implies that a business must refrain from changing its accounting policy unless on reasonable grounds. If for any valid reasons the accounting policy is changed, a business must disclose the nature of change, the reasons for the change and its effects on the items of financial statements.
Consistency concept is important because of the need for comparability, that is, it enables investors and other users of financial statements to easily and correctly compare the financial statements of a company.