When your tax refund suddenly slows down or your WMR status stops updating, most people think a real person decided something was suspicious. In reality, the IRS uses automated scoring systems that rank every tax return by potential risk. Two of the most important systems are the DIF score and the RIVO review flags.

Below is a plain-language explanation of what those systems actually look for and why your return might be routed into a manual review even when you did everything right.

What Is the DIF Score? (The IRS Audit Formula)

DIF stands for Discriminant Inventory Function. It is a mathematical algorithm that compares your return to millions of prior returns and determines how likely it is that something on your return is inaccurate or out of statistical range.

In other words:
The DIF score predicts audit potential based on statistical patterns.

The IRS never releases the exact formula, but the DIF score looks at:

• unusually high deductions
• income that suddenly drops or jumps
• high Schedule C expenses
• refundable credit claims
• dependents claimed inconsistently
• self-employment losses
• EITC or ACTC patterns
• new OBBB deductions (2026 rules)

A high DIF score does not mean you made a mistake. It simply means the computer thinks it should be checked by a human.

What Is RIVO?

RIVO stands for Return Integrity and Verification Operations.
This unit handles the most serious review situations such as:

• identity theft
• refund fraud trends
• questionable wage withholding
• stolen SSNs
• manufactured income

If RIVO touches your file, the refund is usually frozen until the issue is cleared.

How the DIF Score and RIVO Work Together

Here is the real process:

1. DIF score ranks your return for risk
2. If the risk is high, the return is routed for human review
3. If fraud indicators exist, RIVO applies a freeze (often a P-Freeze or C-Freeze)
4. Refund stays on hold until verification or documentation is completed

This all happens before anyone at the IRS has contacted you.

Top Red Flags That Trigger a High DIF Score

The most common triggers are:

• large refundable credits (EITC/ACTC)
• new OBBB deductions for 2026
• sudden income changes
• new dependents
• large Schedule C expenses
• missing Form 8962 (Premium Tax Credit)
• self-employment losses multiple years in a row

The IRS computer compares you to others with similar jobs and similar earnings. If your numbers don’t look normal compared to your peer group, your DIF score rises.

Does a High DIF Score Mean an Audit?

Not always.

A DIF score means:

• extra review
• slower processing
• more verification checks

It can lead to an audit, but most high-score returns only get documentation requests (letters) or additional identity verification.

How to Lower Audit Risk Before Filing

The simplest way to avoid DIF-based delays:

• report exact wage amounts
• match dependent SSNs correctly
• avoid rounding income
• attach required forms
• avoid handwritten numbers
• triple-check direct deposit info
• make sure credits match eligibility

Electronic filing dramatically lowers error rates because numbers are validated before filing.

When RIVO Intervenes

RIVO usually becomes involved when:

• the return contains fabricated income
• a stolen identity is used
• wage withholding cannot be verified
• multiple returns use the same SSN
• a Manual Refund request is made
• refund amount appears unusually large

These cases can be delayed months.

How to Check If You Were Selected

Look at your IRS transcript for:

• TC 570 (refund hold)
• TC 971 (notice generated)
• P-Freeze
• C-Freeze
• DLN numbers with “777” (RIVO indicator)

If you see these, a review is already active.

The IRS is not manually picking your return for audit. Automated scoring systems do it based on statistical models. Your DIF score determines whether your return is normal compared to millions of others, and RIVO steps in only if something suggests potential fraud.

Understanding these systems helps reduce anxiety and gives you a clearer picture of why refunds sometimes slow down, even when nothing is wrong.