This bill, titled the IRS Whistleblower Program Improvement Act, aims to significantly enhance the effectiveness and fairness of the Internal Revenue Service's whistleblower program. It introduces several key changes designed to protect whistleblowers and ensure timely and equitable compensation for their contributions to tax enforcement. A major provision establishes that the Tax Court will conduct a de novo review of whistleblower award determinations, allowing for consideration of new evidence beyond the administrative record. To further protect whistleblowers, the bill grants them the right to proceed anonymously before the Tax Court, unless a compelling societal interest for disclosure outweighs potential harm. Additionally, the legislation mandates that the IRS's annual whistleblower report include a list and descriptions of the top 10 tax avoidance schemes disclosed by whistleblowers, increasing transparency and public awareness. The bill also addresses financial aspects of the program by requiring the IRS to pay interest on whistleblower awards if a preliminary award recommendation is not issued within 12 months of all proceeds being collected and liabilities finalized. Finally, it corrects a technical issue regarding the deduction for attorney's fees, broadening its applicability for whistleblowers.