Dynamic scoring for tax legislation has been discussed for some time. House Rule 13 has required, since 2003, that the Joint Committee on Taxation (JCT) provide a macroeconomic impact analysis of legislation to amend the Internal Revenue Code, or a statement explaining why it is not calculable. The current Senate Budget Resolution (S.Con.Res. 8) includes a similar provision for the Congressional Budget Office (CBO) and JCT. These estimates are not part of the official revenue estimate, but could affect views on legislative proposals.