Tax Legal Services · Primary-source case analysis

Cheek: A Good-Faith Tax-Law Misunderstanding Can Negate Criminal Willfulness

By Aneeta Mishra and Timothy Chan

Published August 18, 2026

Cheek v. United States reviewed convictions for willful failure to file returns and willful tax evasion after an airline pilot asserted that his study of the tax system led him to believe wages were not taxable and returns were not required.

Criminal tax willfulness requires a known legal duty

The government must prove a voluntary, intentional violation of a duty the law imposed and the defendant knew. The requirement responds to the complexity of federal tax obligations.

A claimed misunderstanding is evaluated for actual good faith

A jury may consider the belief’s unreasonableness as evidence about whether it was genuinely held, but a court may not convert objective unreasonableness alone into a rule that the belief cannot negate willfulness.

Constitutional disagreement is different

A person who knows what the tax law requires but believes the requirement is invalid has not misunderstood the duty. Views that the tax statutes are unconstitutional do not negate willfulness under this rule.

The convictions were vacated and the case remanded

The jury instructions improperly restricted consideration of claimed misunderstandings. The Court did not endorse the tax-protester positions or decide that Cheek actually acted in good faith.

Key takeaways

• Separate misunderstanding of a tax duty from disagreement with a known duty.
• Preserve records showing what the taxpayer was told, read, filed, and understood.
• Evaluate consistency between the claimed belief and the taxpayer’s conduct.
• Do not present Cheek as validating arguments that wages are not income or that the tax laws are unconstitutional.