CLIA Regulations Explained (42 CFR 493)

23 October 20268 min read

The CLIA regulations are 42 CFR Part 493: every rule a US clinical lab follows, from its certificate to its quality control to its inspections. This page maps the part letter by letter, says in plain words what each subpart asks, and points to the page here that explains it. The table of contents was read on eCFR on 23 October 2026.

Frosted-glass render of a long row of small dishes, each holding one lab object — A long row of dishes, one object in each: the regulation laid out one subpart at a time.

42 CFR 493 at a glance

The CLIA regulations are one part of the Code of Federal Regulations, 42 CFR Part 493, cut into lettered subparts from A to T. 14 of them carry rules today; the rest are reserved, held empty. Pick a letter to jump to it.

in force
reserved

ASubpart A, General Provisions
BSubpart B, Certificate of Waiver
CSubpart C, Registration Certificate, Certificate for Provider-performed Microscopy Procedures, and Certificate of Compliance
DSubpart D, Certificate of Accreditation
ESubpart E, Accreditation by a Private, Nonprofit Accreditation Organization or Exemption Under an Approved State Laboratory Program
FSubpart F, General Administration
GSubpart G, reserved
HSubpart H, Participation in Proficiency Testing for Laboratories Performing Nonwaived Testing
ISubpart I, Proficiency Testing Programs for Nonwaived Testing
JSubpart J, Facility Administration for Nonwaived Testing
KSubpart K, Quality System for Nonwaived Testing
LSubpart L, reserved
MSubpart M, Personnel for Nonwaived Testing
NSubpart N, reserved
OSubpart O, reserved
PSubpart P, reserved
QSubpart Q, Inspection
RSubpart R, Enforcement Procedures
SSubpart S, reserved
TSubpart T, Consultations

What is CLIA?

CLIA is the Clinical Laboratory Improvement Amendments of 1988, the federal law on laboratory testing of people in the United States. (The cruise industry's trade group shares the initials; this page is about the lab law.) The rules that carry it out are 42 CFR Part 493, and § 493.1 says they set the conditions “all laboratories must meet to be certified to perform testing on human specimens”.

“Laboratory” is defined broadly in § 493.2: any facility examining “materials derived from the human body for the purpose of providing information for the diagnosis, prevention, or treatment of any disease or impairment of, or the assessment of the health of, human beings.” A physician's office running a urine dipstick is a laboratory. A site that only collects or ships specimens is not. Three kinds of testing fall outside the rules (§ 493.3(b)): forensic-only testing, research that never reports patient-specific results, and drug testing in labs certified by SAMHSA under its own rules.

301,284

laboratories registered under CLIA, exempt and non-exempt

CMS, September 2026

285,940

non-exempt laboratories, outside the New York and Washington state programs

CMS, September 2026

Frosted-glass render of a well plate filled row by row from one tint to the other — Filled row by row: the subparts in order, the reserved ones left open.

The subparts, A to T

Every subpart below is listed with eCFR's own title and its first and last section, read from the eCFR table of contents on 23 October 2026. The letters link to the text; the right-hand column goes to the AssayDeck page that explains it.

The subparts of 42 CFR 493, what each covers, and the AssayDeck pages on each
Subpart	eCFR title	In plain words	On AssayDeck
A	General Provisions§ 493.1–493.25	Who CLIA covers, the definitions, and how tests are sorted into waived, PPM, moderate and high complexity.	Test complexity Waived tests
B	Certificate of Waiver§ 493.35–493.41	Applying for and keeping a certificate of waiver, and the changes a waived lab must report.	Certificate of waiver Certificate renewal
C	Registration Certificate, Certificate for Provider-performed Microscopy Procedures, and Certificate of Compliance§ 493.43–493.53	Applications for the other certificates: the registration certificate a new nonwaived lab starts on, PPM, and compliance after a survey.	Getting a certificate Certificate finder PPM certificate Form CMS-116 CLIA lookup Certificate renewal
D	Certificate of Accreditation§ 493.55–493.63	Meeting CLIA through a CMS-approved accreditor instead of a State Agency survey.	CAP vs COLA Certificate renewal
E	Accreditation by a Private, Nonprofit Accreditation Organization or Exemption Under an Approved State Laboratory Program§ 493.551–493.575	How accreditors and state programs win and keep CMS approval, and CMS's validation inspections of accredited labs.	Approved accreditors
F	General Administration§ 493.602–493.680	Certificate and survey fees, and how they rise.	Fee calculator
G	Reserved	Held empty; no rules.
H	Participation in Proficiency Testing for Laboratories Performing Nonwaived Testing§ 493.801–493.865	Enrolling in PT, testing samples like patient specimens, never referring them, and the scores that pass.	Proficiency testing PT score calculator
I	Proficiency Testing Programs for Nonwaived Testing§ 493.901–493.959	What an approved PT program must offer: the analytes, the events each year, the acceptance limits.	Approved PT programs CAP vs API
J	Facility Administration for Nonwaived Testing§ 493.1100–493.1105	Facilities, transfusion services, and how long records, reports and slides are kept.	What an LIS keeps
K	Quality System for Nonwaived Testing§ 493.1200–493.1299	The specialty conditions and the general, preanalytic, analytic and postanalytic systems: manual, calibration, QC, records, reports.	How often to run QC Westgard rules IQCP Calibration verification
L	Reserved	Held empty; no rules.
M	Personnel for Nonwaived Testing§ 493.1351–493.1495	Who may direct, consult, supervise and test at each complexity, and what each must do.	Personnel Lab director Competency
N–P	Reserved	Held empty; no rules.
Q	Inspection§ 493.1771–493.1780	Which labs are inspected, how often, and the access a surveyor must be given.	Inspections Inspection checklist
R	Enforcement Procedures§ 493.1800–493.1850	Sanctions when conditions are not met: plans of correction, penalties, certificate action, appeals.	CMS-2567 and plans of correction
S	Reserved	Held empty; no rules.
T	Consultations§ 493.2001	Provides for the Clinical Laboratory Improvement Advisory Committee (CLIAC). CMS says the Secretary terminated CLIAC on 31 March 2025.	Read it on eCFR

Waived labs live mostly in A, B and F; they skip H through M, which apply to nonwaived testing. A lab with one moderate or high complexity test reads the whole table. Subpart Q applies to every certificate type.

How to read a CLIA cite

Surveyors, accreditors and every page on this site cite the rules the same way. Take 42 CFR § 493.1256(d)(3):

42: Title 42 of the Code of Federal Regulations, Public Health
CFR: Code of Federal Regulations
§ 493.1256: Part 493, section 1256 (Standard: Control procedures), in Subpart K
(d)(3): Paragraph (d), subparagraph (3): the once-a-day control rule

The heading tells you the weight. In Subparts J, K and M most sections begin “Condition:” or “Standard:”. A condition, such as Analytic Systems in § 493.1250, is the broad requirement; the standards beneath it, such as control procedures in § 493.1256, are the specific ones. A failed standard is a standard-level deficiency; a serious or pervasive failure is written against the condition, and that is where the sanctions of Subpart R begin. A standard-level finding left open for 12 months gets there too. How a CMS-2567 cites them shows both on the form.

The requirements are the same for Medicare approval as for CLIA certification.

42 CFR § 493.1

Who writes and enforces it

Three federal agencies share CLIA, in CMS's own division of the work (MLN006270, March 2026). Day to day, a lab deals with its State Agency, which surveys for CMS, or with its accreditor.

CMSIssues certificates, collects fees, inspects and enforces, approves accreditors, state exemptions and PT programs, and writes the CLIA rules.
FDASorts tests into waived, moderate and high complexity, reviews waiver applications, and writes the categorization rules.
CDCRuns quality studies, writes technical standards and practice guidelines, monitors PT practices and gives technical help.

Frosted-glass render of a slide box, a control chart under glass and a sample kit grouped together — Slides, a control chart and a sample kit: the records the rules ask a lab to keep.

What may change: the October 2026 proposal

On 8 October 2026 CMS published a proposed rule, CMS-3478-P (91 FR 64480). It is a proposal, not law: every rule on this page stays as written until CMS publishes a final rule. Comments close on 7 December 2026 (Federal Register). As proposed, it would:

allow virtual access, so staff could review data remotely under the primary lab's certificate, except in cytology;
allow digital images in gynecologic cytology proficiency testing;
revise personnel qualifications in Subpart M;
remove the SARS-CoV-2 reporting condition;
add the CLIA number and the laboratory's name to every test report;
revise parts of the enforcement rules, and make the advisory committee in Subpart T optional (“will” becomes “may”).

Caution

Proposed only

Plan for it, but do not change a procedure because of it until a final rule appears in the Federal Register.

Takeaway

Read 42 CFR 493 by letter: your certificate decides which letters apply, and each letter has one page here that explains it in plain words.