Wilful blindness is a state of mind in which a person suspects a fact, has the means to confirm it, and deliberately chooses not to inquire so as to avoid confirming what they suspect. In tax matters, courts treat wilful blindness as equivalent to actual knowledge when assessing whether conduct supports a gross-negligence penalty or, in criminal cases, the intent required for tax evasion.
The concept frequently arises where a taxpayer signed a return prepared by someone else without reviewing obviously inflated deductions or fictitious losses. Establishing wilful blindness requires more than carelessness; it requires a deliberate decision to remain ignorant. Distinguishing genuine reliance on an adviser from a choice not to ask questions is often central to the analysis.