An accounting rule that an entity applies to govern specific classification and measurement considerations in all cases, including any case (even if substantiated) that cannot be made to rebut/ invalidate that rule. In other words, it is an inference or assumption that a fact exists, which cannot be refuted by any additional evidence or argument.

An irrebuttable presumption is a conclusive inference of a particular fact- i.e., it describes a fact or statement that cannot be challenged and hence it is considered absolute in its establishment and effects. For example, irrebuttable presumptions can be used to establish a minimum accounting tax, where tax liability is assumed to be at least equal to the amount determined under a set of presumptive rules.

Irrebuttable presumption is the opposite of a rebuttable presumption.