The Key Differences Between a Standard IRS Income Review and a Serious Identity Theft Investigation

Nothing disrupts refund season faster than receiving an IRS letter. But not all IRS correspondence signals the same level of delay. Two of the most common letters—CP05 and 2645C—both involve refund holds, yet they trigger very different review processes and dramatically different wait times.

If you received one of these letters, it’s essential to understand what it means, what the IRS is reviewing, and how long the refund delay will last.

Here is the breakdown you need to understand the difference between CP05 and 2645C and which one leads to the longest review.

What Is IRS Letter CP05?

Letter CP05 is one of the most common IRS notices during tax season. It means:

• The IRS is verifying your income
• The IRS is verifying your withholding
• The IRS is checking refundable credits (CTC, EITC, AOTC, etc.)
• Your refund is temporarily held
• No documents are requested—yet

CP05 is primarily part of the IRS’s standard income verification process.

What the IRS Checks Under CP05

• W-2 matching with employer records
• 1099 matching
• Dependent information
• EITC or CTC eligibility
• Withholding accuracy

CP05 is a routine review, not a fraud investigation.

Average CP05 Timeline

45–60 days
Sometimes faster if IRS systems automatically match your income records.

CP05 is frustrating, but it is not a severe case.

What Is IRS Letter 2645C?

Letter 2645C is a much more serious notice. This letter is sent when:

• Your return is under identity theft investigation
• The IRS must confirm your identity
• A fraudulent return may have been filed using your SSN
• Your return is locked in the identity theft unit
• The IRS needs more time to work your case—often a lot more time

Letter 2645C does not ask for documents. It simply acknowledges that:

• The IRS received your identity theft claim
• Additional review time is required
• Processing will take significantly longer

This letter is usually connected to Transcript Code 810 (Refund Freeze) or long-standing TC 570 holds.

Average 2645C Timeline

120–180 days
Many cases take even longer, especially if:

• Fraud occurred before filing
• Multiple returns were filed using your SSN
• Employer wage data is inconsistent
• Child dependents were also compromised

Letter 2645C is one of the longest refund delays in the IRS system.

CP05 vs. 2645C: Summary of the Key Differences

A CP05 letter means your refund is slowed.
A 2645C letter means your refund is stopped until identity issues are resolved.

Why CP05 Happens

Letter CP05 is triggered when:

• Employer wage reports are delayed
• Matching systems flag your withholding
• A dependent appears on multiple returns
• Credits like EITC, ACTC, or AOTC need verification
• Income numbers appear inconsistent

CP05 usually clears once IRS computers verify everything automatically.

Why 2645C Happens

Letter 2645C is sent when:

• Your identity theft claim was received
• A fraudulent return was filed using your SSN
• The IRS must freeze your account to prevent additional fraud
• A deep manual review is required
• Multiple agencies may need to verify records

This is part of the IRS’s Identity Protection Program, not ordinary processing.

What to Do If You Received a CP05 Letter

For CP05:

• Wait for the IRS review period to complete
• Do not resend your tax return
• Respond only if the IRS later requests documents
• Monitor your transcript for TC 571 or TC 846

Your refund should release once the income verification completes.

What to Do If You Received a 2645C Letter

For 2645C:

• Expect a long delay
• Complete identity verification if not already done
• File Form 14039 if identity theft is involved
• Monitor for TC 971 (notice sent), TC 810 (freeze), or TC 570 (hold)
• Call the IRS Identity Protection unit if deadlines pass
• Consider contacting the Taxpayer Advocate Service for severe hardship

Identity theft cases require patience—no shortcuts exist.

Which Letter Causes the Longer Refund Delay?

Letter 2645C by far.

CP05 = 45–60 days
2645C = 120–180+ days

CP05 is a routine review.
2645C is a serious identity theft investigation.

One is temporary.
The other is extensive.

Transcript Clues That Reveal Which Review You’re In

CP05 Signs

• TC 570 (single hold)
• No fraud freeze codes
• TC 150 posted normally
• Employer/credit matching pending

2645C Signs

• TC 810 (refund freeze)
• TC 971 linked to identity theft
• TC 570 without movement for months
• Duplicate return indicators
• Identity verification letters (5071C or 5747C)

These clues help confirm the depth of your review.

IRS letters CP05 and 2645C both delay refunds, but they indicate vastly different situations:

• CP05 is a standard income verification review with a relatively short delay.
• 2645C is an identity theft acknowledgment that can lead to one of the longest refund holds in the IRS system.

Knowing which letter you received helps you understand the likely timeline, the steps needed to resolve the issue, and whether your refund is simply delayed—or completely frozen pending identity theft investigation.