Filing a return constitutes a waiver of Fifth Amendment rights
The claim
Some advocates argue that the act of filing a federal income tax return waives Fifth Amendment protection against self-incrimination — because the return contains information that could be used to prosecute the filer for unrelated offenses. The argument concludes that the filer may invoke the Fifth and decline to file at all.
The authority
United States v. Sullivan, 274 U.S. 259 (1927), addressed precisely this question and rejected it. The Court held that the Fifth Amendment does not excuse the filing requirement; it only protects the filer from being compelled to disclose specific incriminating information within the return. A taxpayer may invoke the privilege as to particular line items but cannot use it to refuse filing entirely. The distinction has been consistently applied for nearly a century.
Verdict
Unsupported. Sullivan is a directly on-point Supreme Court decision that disposes of the argument. The Fifth Amendment is a privilege against specific compelled testimony, not a general exemption from the filing requirement.