Key Takeaways

  • CAF number is a unique 9-digit ID assigned to practitioners.
  • Used to track authorizations (2848/8821) in the IRS computer system.
  • First-time users should write "NONE" in the CAF number box.
  • Specific tax forms and years are recorded; general authorizations are NOT.
  • Future years limited to 3 years in advance.
  • CAF number is different from PTIN and SSN.
Last updated: January 2026

Centralized Authorization File (CAF): The IRS Tracking System

Why This Matters for the Exam

The CAF system is how the IRS tracks who is authorized to represent which taxpayers. Understanding how CAF numbers are assigned, what gets recorded, and what doesn't is essential for Part 3.

Expect at least 2-3 questions on CAF numbers and recording requirements.

What Is the CAF?

The Centralized Authorization File (CAF) is the IRS database that stores information about third-party authorizations (Forms 2848 and 8821). It allows IRS employees to verify who can receive taxpayer information or represent a taxpayer.

The CAF Number

CharacteristicDetail
Format9-digit number
Assigned ByIRS (after first Form 2848 or 8821 is processed)
Unique ToEach representative
NOT the Same AsPTIN (preparer tax ID) or SSN

First-Time Representatives: If you don't have a CAF number yet, write "NONE" in the CAF number box. The IRS will assign one after processing your first authorization form.

What Gets Recorded in CAF?

The CAF system records specific authorizations:

RecordedNot Recorded
Specific tax form types (1040, 941, etc.)"All tax forms"
Specific tax years (2022, 2023, 2024)"All years"
Specific tax periods (Q1 2024, etc.)Open-ended periods
Civil penalties for specific yearsGeneral penalty inquiries

Key Rule: Authorizations for "all years" or "all matters" are not recorded in CAF. They remain valid but only for the specific IRS office that receives them—they won't appear in the national CAF database.

Future Year Limitations

The CAF system can record authorizations for future tax periods, but with limits:

  • Maximum: 3 years beyond the current year.
  • Example: In 2025, you can authorize representation for years up to 2028.
  • Rationale: Prevents indefinite authorizations; encourages periodic renewal.

CAF vs. PTIN vs. EFIN

ID TypePurposeFormat
CAF NumberAuthorization tracking9 digits
PTINPreparer identification (for signing returns)P + 8 digits
EFINE-file provider identification6 digits
SSNPersonal identification9 digits (XXX-XX-XXXX)

How the CAF System Works

  1. Practitioner files Form 2848 or 8821 with the IRS.
  2. IRS processes the form and enters the authorization into CAF.
  3. IRS assigns CAF number (if first authorization for that practitioner).
  4. Authorization appears in IRS systems, allowing the practitioner to access taxpayer info.
  5. Practitioner uses CAF number on all future Forms 2848/8821.

Real-World Scenario

Scenario: You're a new EA filing your first Form 2848 for a client's 2023 and 2024 Form 1040 audits.

  • CAF Number Box: Write "NONE" (you'll receive a CAF number after processing).
  • Tax Form Type: Enter "1040" (specific form).
  • Tax Years: Enter "2023" and "2024" (specific years).
  • Future Years: You could add "2025" if the client wants ongoing representation.

After processing, you'll receive your CAF number and use it on all future authorization forms.

On the Exam

Expect 2-3 questions on CAF, typically:

  1. First-Time Questions: "What should a practitioner without a CAF number enter?"
  2. Recording Questions: "Which authorization is NOT recorded in CAF?"
  3. Limitation Questions: "How many future years can be recorded?"

The key is to remember: CAF = 9 digits, "NONE" for first-timers, specific forms/years only, 3-year future limit.

Test Your Knowledge

What should a practitioner write on Form 2848 if they do not yet have a CAF number?

A
B
C
D
Test Your Knowledge

Which of the following authorizations will NOT be recorded in the CAF system?

A
B
C
D
Test Your Knowledge

How many years into the future can CAF record authorizations?

A
B
C
D