New Finding Aids on eCFR.gov

We’re excited to announce the release of two Finding Aids on eCFR.gov — the Subject Index and the Parallel Table of Authorities. Both are now available online and, for the first time, both are updated in real time.

What’s changed

Until now these compilations have been produced manually and, because of the effort involved, published only once a year. A reader looking for the Parts that address a given subject, or the CFR Parts issued under a given statutory authority, was working from a snapshot that could be up to twelve months old.

Using FederalRegister.gov and eCFR.gov data sources, we have automated the creation of both compilations and can now offer them in real time on eCFR.gov.

A New Look for Finding Aids

As part of our latest release, we updated the top navigation bar to streamline user access and improve the organization of both new and existing content across the site.

• The Corrections menu item has been replaced by Finding Aids. This section consolidates essential research tools and introduces three new resources:
  • Parallel Table of Authorities
  • Subject Index
  • Agency-prepared Indexes
• The Recent Changes menu has been renamed CFR Updates to offer a clearer description of its contents. It now provides access to:
  • Recent Changes
  • Issue Summaries
  • Corrections (relocated from the primary navigation bar)

Finding Aids pages also carry a new design treatment that identifies them as a distinct resource on eCFR.gov, separate from other Reader Aids or the content of the CFR itself.

Subject Index

The Subject Index updates automatically any time a Federal Register rule document that modifies the CFR becomes effective and contains a List of Subjects for the Part(s) it modifies. Any List of Subjects items matching the approved thesaurus appear on eCFR.gov and link directly to the associated CFR content.

The online Subject Index is also more capable than the print version, which print space and costs constrained to a basic lookup index:

• Part titles included: Each reference shows the title of the Part it points to, so you can tell what you’re navigating to before you click.
• Grouping and filtering: Group by topic or by CFR Title, and limit results to the topics or titles you care about.
• Quick search: Jump straight to a reference if you already have an idea of the one you want.

For agency users drafting Federal Register documents, the up-to-date thesaurus is now available on eCFR.gov as well.

Parallel Table of Authorities

The Parallel Table of Authorities is extracted directly from the Authority portions of the CFR content. Any time a change is codified that modifies Authority content, the table is automatically updated.

As with the Subject Index, we’ve added context and tools that the abbreviated print references lack:

• Part titles included: See what each authority points to instead of a bare citation.
• Grouping and filtering: Group by Authority or by CFR Title, and filter to a certain type of authority or title number.
• Quick search: Navigate directly to a reference you already know.

Viewing Earlier Editions

If you are working with content from a specific date, or tracing how a subject or an authority was indexed at the time, you may want the compilation as it stood then — not as it stands today.

Both new Finding Aids resources include a Date selector alongside the grouping and filtering controls. Leave it set to Current for the most up-to-date compilation, or choose a year to view that year’s edition instead. The year you select is carried in the URL, so a link to a specific edition — for example the 2025 Subject Index or the 2025 Parallel Table of Authorities — stays pointed at that edition when you cite or share it.

This mirrors how the rest of eCFR.gov works. Just as the point-in-time system lets you view the regulations as they read on a past date, the Finding Aids now let you view the compilations as they were published for a past year.

What’s Next

We’re continuing to expand what eCFR.gov can do – let us know how we can improve this feature or what you’d like to see next, by using the Site Feedback button in the lower right corner of any page.