“Legislative Intent” is what the court wants to determine from evidence that appears in documents that consist of a bill’s legislative history. “Legislative intent” and “legislative history”, though different concepts, have become interchangeable among practitioners.
Tax bills must generally clear three Congressional committees before facing the votes of the full House and Senate to become an enrolled bill: the House Ways and Means Committee, the Senate Finance Committee, and the Joint Committee on Taxation (the Conference Committee, usually numbered as a House Conference Report). The Committee Reports are the documents to locate when assembling evidence of what the legislature intended. Committee reports are documents of persuasion, often arguing the best expression of public policy reasoning Congress might provide, with a heavy emphasis on “might”.
Committee reports and other legislative commentary can be found in:
Internal Revenue Bulletin KF6301.A35.A2. Published weekly online, no longer in print, the IR Bulletin's Part II(B) contains current tax legislation and related committee reports. Not well indexed, the IR Bulletin's Finding Lists are helpful once you have a citation. Better, please see https://www.irs.gov/irb
Cumulative Bulletin KF6301.A35.A2. A museum piece. This was the bound compilation of the Internal Revenue Bulletin. Tax legislation and related committee reports are usually published in the third volume. Again, not well indexed, but the Tables of Contents are fairly detailed. See also the Finding Lists, located in the front of each volume.
BNA's Daily Tax Report contains current legislation, committee descriptions of the contents of tax legislation, and provides a detailed legislative calendar, with citations to committee reports, bills, and resolutions.
CCH / Vitallaw's Standard Federal Tax Reporter. While the Standard Federal Tax Reporter does not contain the text of Congressional committee reports, Cumulative Bulletin citations to committee reports are provided in the Citator Volume M-Z in the Finding Lists. The Finding List gives the Internal Revenue Code section number amended that year, followed by the related public law number and the location of relevant committee reports in the Cumulative Bulletin.
Westlaw’s Legislative History materials are all but unsurpassed.
Lexis offers access to documents from the Congressional Information Service, which has published every document Congress has issued since 1969. CIS cost this library $40,000 per year as late as 2010. Lexis no longer offers CIS to law schools. Instead, Lexis brags about its database of Committee Reports. Can we search these by Public Law Number? Of course not.
Lexis’s anti-customer reasoning argues, when the resolution was in committee, it was not a public law yet, so it didn’t have a public law number. This means, the researcher must first locate the main bill that was eventually enacted, keeping in mind that much legislation combines multiple bills before they are harmonized into the main bill that passes both houses of Congress. Lexis forgets that no one cares about legislative intent until provisions of a public law are being litigated, at which time the litigants all have code sections and the public law numbers from which they were codified. But Lexis wants us to spend time looking for bill numbers to use as search terms for its committee reports.
I use the time I could have squandered looking for and sifting bill numbers by instead following the legislative history links that Westlaw provides for most of its code sections and public laws.
See, also: Vitallaw’s Federal Tax - Major Tax Acts and Reports (1986-2022)