USC vs CFR: What the Abbreviations Mean and How They Differ

Short answer: in USC vs CFR, U.S.C. stands for United States Code. It holds the federal laws that Congress passes. C.F.R. stands for Code of Federal Regulations. It holds the detailed rules that federal agencies write, using power a law in the U.S. Code gave them. Congress sets the rule in the Code, and an agency fills in the details in the CFR. You will often need both to answer one question.

TL;DR

• U.S.C. is the United States Code. Congress writes the laws in it. It has 54 titles (broad subject areas).
• C.F.R. is the Code of Federal Regulations. Agencies write the rules in it. It has 50 titles.
• A citation is an address. "29 U.S.C. § 2654" means title 29 of the Code, section 2654. "29 C.F.R. § 825.100" means title 29 of the CFR, section 825.100.
• The link between them is an authority line. Each CFR part names the law that lets the agency make the rules.
• The same title number does not always mean the same subject in both books.

What does U.S.C. stand for?

It stands for United States Code. Read a citation such as 29 U.S.C. § 2654 from left to right:

• 29 is the title number. A title is one of the Code's big subject areas. Title 29 is Labor.
• U.S.C. names the book.
• § is the section sign. It means "section".
• 2654 is the section number.

The House of Representatives' Office of the Law Revision Counsel publishes the Code. It says the Code holds the "general and permanent laws of the United States", arranged by subject into 54 titles. "General and permanent" leaves out laws that expire, such as a one-year spending bill.

Two other letters you may meet are U.S.C.A. and U.S.C.S. Those are private publishers' editions of the same Code with added notes.

What does C.F.R. stand for?

It stands for Code of Federal Regulations. A regulation is a rule written by a government agency. Agencies first publish new rules in the Federal Register, the government's daily journal. The CFR then collects the agencies' general and permanent rules, according to the National Archives, which has published it since 1938.

A citation such as 29 C.F.R. § 825.100 reads in the same order:

• 29 is the title number. Title 29 is Labor.
• C.F.R. names the book.
• 825 is the part, a group of rules on one topic. Part 825 covers family and medical leave.
• 100 is the section inside that part. The dot joins the two numbers.

The National Archives says the CFR has 50 titles. Each title is split into chapters, which usually carry an agency's name. Chapters are split into parts, and parts into sections.

The eCFR, short for electronic CFR, is the free online version at ecfr.gov. It is updated daily.

One trap: the letters also mean other things in other fields. CFR is a shipping term, and USC is also a university. If a search page shows those, add "law" to the search.

What is the difference between USC and CFR?

Who writes it. Congress writes the Code. Both chambers vote, and the president signs or Congress overrides a veto. An agency writes the CFR. It must follow a public process: usually it proposes a rule, takes comments, then publishes a final rule.

Where the power comes from. An agency cannot make rules from nothing. A law in the Code must hand it that power. Our guide to what a regulation is covers this. A court can strike down a rule that goes past what the law allowed.

How much detail. Congress usually sets the main rule and leaves the fine points to the agency.

USC vs CFR side by side

One law traced to its rule: family and medical leave

Take a question a small employer faces: how much leave must you give a worker who has a baby or a serious illness?

Step 1: the law in the Code. Congress passed the Family and Medical Leave Act in 1993. Section 2612(a)(1) of Title 29 says an eligible employee "shall be entitled to a total of 12 workweeks of leave during any 12-month period" for reasons such as a birth, an adoption or a serious health condition. Look at one detail. It lets leave be taken for "any qualifying exigency (as the Secretary shall, by regulation, determine)". An exigency is an urgent situation. Congress left the definition to the Secretary of Labor.

Step 2: the instruction to write rules. Section 2654 of the same title is short. It says: "The Secretary of Labor shall prescribe such regulations as are necessary to carry out subchapter I and this subchapter not later than 120 days after February 5, 1993." This is the permission slip. The GovInfo 2024 edition of 29 U.S.C. § 2654 shows the text. The Code section does not name the rule that resulted. The link is easier to follow from the other side.

Step 3: the rule in the CFR. The Department of Labor wrote Part 825 of Title 29. Open 29 C.F.R. Part 825 on the eCFR and look just under the part heading, where it reads "Authority: 29 U.S.C. 2654" (followed by two other sources of authority). That one line ties the whole part back to section 2654. Section 825.100 restates the entitlement in working terms: eligible employees may take "up to a total of 12 workweeks in any 12 months". Section 825.126 then does the job Congress left open. It says employees may take leave for a qualifying exigency "while the employee's spouse, son, daughter, or parent" is on covered active duty, and it spells out what counts.

Notice what each book did. Congress fixed the 12 weeks. The agency set the working details, such as notice and paperwork. Section 2654's credit line (the note under it that lists each law that made or changed it) names only the 1993 act. Part 825 has been amended many times. The eCFR's version history shows a change to section 825.300 as recently as January 2025. The note at the top of the part, headed "Source", points to a Federal Register rule published on February 6, 2013. The eCFR said it was current as of October 1, 2026, when we read it on October 5, 2026.

For a business question, start with the CFR for the day-to-day duties. Then check the Code for the limits the agency has to stay inside.

How to find each one on an official site

1. For the Code, go to uscode.house.gov. Type the citation, or pick the title and browse down to the section. The online Code is updated as new laws pass. The site govinfo.gov hosts official editions by year.
2. For the CFR, go to ecfr.gov. Pick the title, then the part. The eCFR calls itself "an informational resource". The formal text is the annual edition on govinfo.gov. GovInfo's CFR page explains the schedule. Title 29 is revised as of July 1 each year.
3. To go from rule to law, read the authority line at the top of the CFR part.
4. To go from law to rule, search the CFR for the Code citation, for example "29 U.S.C. 2654". Authority lines contain it.

Our guide to how to cite a statute or regulation shows how to write what you found down.

What goes wrong

• Treating the two as the same thing. A Code section can say "the Secretary shall define it". The definition lives in the CFR.
• Assuming matching title numbers match in subject. Title 40 of the Code is Public Buildings, Property, and Works. Title 40 of the CFR is Protection of Environment.
• Reading only one side. The Code gives the rule's reason and limits. The CFR gives the working detail.
• Using an old copy. The yearly CFR edition can be months behind the eCFR. A rule may have changed since it was printed.
• Using the wrong government. These are federal books. Your state has its own code and its own rules. Our primer on primary law shows how federal and state layers fit together.
• Relying on a summary. A fact sheet or chatbot is not the text. Open the section.

This is general information, not legal advice. For a decision with real risk, ask a lawyer licensed in the right state.

This guide is part of US Law Data: The Complete Guide.

FAQ

What does CFR stand for? CFR stands for Code of Federal Regulations. It is the set of rules that federal agencies write to carry out laws. It has 50 titles, and each rule is cited by title, part and section, such as 29 C.F.R. § 825.100.

What does USC stand for? USC stands for United States Code when it is used in law. It collects the general and permanent federal laws in 54 titles. Written with periods, U.S.C., it always comes after a title number and before a section number.

What is the difference between USC and CFR? Congress writes the USC and agencies write the CFR. The USC holds the law itself. The CFR holds the rules an agency makes under authority that a law in the USC gives it.

Is the CFR a law? Yes. A valid rule in the CFR binds people and businesses much as a law does. That holds when the agency stayed within the power the law gave it. A court can strike one down if the agency went too far. When a rule and its law seem to disagree, the law is the starting point.

Which comes first, the USC or the CFR? The USC comes first. An agency needs authority from a law before it can write a rule, and that authority is named in the rule's authority line. The rule is then added to the CFR after it appears in the Federal Register.

Do I cite the U.S.C. or the C.F.R.? Cite the one you are relying on, and often both. If you are describing what Congress required, cite the U.S.C. If you are describing how an agency applies it, cite the C.F.R. Give the exact section so a reader can find the same words.

Where can I read the USC and CFR for free? Both are free on official sites. The Code is on uscode.house.gov and govinfo.gov, and the CFR is on ecfr.gov and govinfo.gov. Check the date on the page before you rely on any text.

If you want the law and regulation text behind guides like this one in your own product, see the Vaquill AI legal data API.

Priyansh Khodiyar

Co-Founder & CTO

Priyansh leads engineering and AI at Vaquill AI: the pipelines that pull statutes, regulations and court rules from every US jurisdiction's official publisher, and the REST API, MCP server and open dataset that serve them.