Tax benefit defined to include tax reductions, deferments, refund increases, income reductions and loss increases under income tax law. Under Chapter X-A, Tax benefit is an expansive concept comprising reduction, avoidance or deferral of tax or other amounts payable under the Act; increases in refunds under the Act; analogous reductions or refund increases resulting from a tax treaty; and reductions in total income or increases in loss in the relevant previous year or any other previous year.