ConceptAuthority HierarchyPrimary: IRC, Treasury Regulations, Tax Treaties. Secondary: Revenue Rulings, PLRs, TAMs. Courts: Supreme Court, Circuit Courts, Tax Court, District Courts.
Key PointStatute of Limitations3 years from filing. 6 years if >25% gross income omitted. Unlimited for fraud or non-filing.
ConceptPenaltiesAccuracy: 20% of underpayment. Fraud: 75%. Failure to file: 5%/month up to 25%. Failure to pay: 0.5%/month up to 25%.