Consistency concept definition including break down of areas in the definition. Analyzing the definition of key term often provides more insight about concepts. Consistency concept can be defined as: Principle that prescribes use of the same accounting method(s) over time so that financial statements are comparable across periods. Consistency concept is a concept that would suggest we should use consistent accounting methods, if all else is equal. For example, if we start using first in first out as an inventory cost flow assumption we should continue with this cost flow assumption. The consistency concepts applies in a similar way to all uses of accounting estimates and methods.