Every year, millions of tax returns are delayed, rectified, or altered due to discrepancies between taxpayer and employer revenue. These situations—called wage mismatches—are one of the most common reasons the IRS sends unexpected refunds, reduced refunds, or even surprise deposits labeled IRS TREAS 310 TAX REF or INT REF.

Most taxpayers never realize a wage mismatch occurred until a correction is made long after filing. Some discover it only when the IRS issues:

• An unexpected refund deposit
• A CP12 or CP21A notice
• A transcript change, often months later
• A recalculation of credits

This tutorial describes how wage mismatches occur, why employer adjustments influence your taxes, and how these difficulties lead to IRS TREAS 310 payments—sometimes years after you filed.

What Is an IRS Wage Mismatch?

An IRS wage mismatch occurs when the wages or withholding you report on your tax return don’t match what your employer reports to the IRS on:

• Form W-2
• Form 1099-NEC
• Form 1099-K (third-party payments)
• Form 1099-MISC

The IRS certifies your return based on the income data provided by employers initially.

If something doesn’t match, the IRS automatically recalculates your return.

Common triggers include:

• Employer submitted a corrected W-2 (W-2C)
• Employer filed wages late
• Wages were reported under the wrong Social Security Number
• Employer withheld the wrong amount of tax
• Payroll system errors
• Multiple employers reporting different figures

When the IRS discovers income or withholding that differs from what you reported, a correction is issued.

How Employer Corrections Trigger IRS TREAS 310 Payments

Employer wage corrections often lead to refund adjustments—either higher or lower.
Here’s how they result in IRS deposits:

1. IRS Recalculates Your Refund Based on Corrected Wages

If the corrected employer information shows:

• More tax withheld than you originally claimed, your refund increases
• Lower income than originally reported, you may qualify for more credits

This often results in an unexpected IRS TREAS 310 TAX REF deposit.

These revisions do not require your permission; the IRS makes the necessary adjustments automatically.

2. Misreported Wages Can Increase Refundable Credits

Several refundable credits depend heavily on correct income numbers:

• Earned Income Tax Credit (EITC)
• Child Tax Credit (CTC)
• Additional Child Tax Credit (ACTC)
• Premium Tax Credit (PTC)

If employer corrections reduce your income or increase your withholding, you may obtain additional credit amounts, resulting in a retroactive IRS refund.

3. IRS Adds Interest for Delayed Refunds (INT REF)

If the correction pushes the refund more than 45 days past the filing deadline, the IRS must pay interest on the amount owing.

This is issued as:

• IRS TREAS 310 INT REF
  or
• Added to your TAX REF deposit

Interest payments frequently arrive unexpectedly.

4. IRS Automatically Corrects Your Return (CP12 or CP21A)

When wage discrepancies arise, the IRS uses automated tools to correct your return.

You may later receive:

• CP12 Notice – IRS corrected an error and adjusted your refund
• CP21A Notice – IRS changed your return based on new information

These notices usually occur after the deposit, not before.

5. Amended W-2 or 1099 Adjustments Arrive Months (or Years) Later

Employers can submit amended salary statements at any time, including a year later.

IRS then:

• Recalculates your past tax return
• Issues a new refund
• Applies interest if applicable

This explains why many taxpayers get IRS TREAS 310 deposits for previous years such as 2021, 2022, 2023, and 2024.

Common Employer Errors That Lead to IRS Refund Adjustments

Here are the most frequent employer mistakes that impact taxpayer refunds:

• • Incorrect income amounts
• • Wrong Social Security Number
• • Underreported withholding
• • Duplicate W-2 transmissions
• • Incorrect retirement contributions coded
• • Wrong dependent care benefits
• • 1099-NEC vs. W-2 classification errors
• • Tips, bonuses, or overtime not included

Any of these may cause your IRS return to be reprocessed months later.

How to Know If an IRS Wage Mismatch Affected You

These signs usually indicate that the IRS corrected your return based on employer data:

1. Your IRS Transcript Shows Adjustment Codes

Look for:

• 290 — Additional Tax Assessed
• 291 — Tax Reduced
• 766 — Credit Applied
• 776 — Interest Credit
• 971 — Notice Issued
• 846 — Refund Issued

These codes represent an IRS recalculation using fresh wage data.

2. You Received a CP12 or CP21A Notice

These notices confirm:

• IRS found errors
• IRS recalculated credits or withholding
• IRS issued a new refund amount

Notices typically occur 7-21 days following a surprise deposit.

3. Your Refund Was Bigger or Smaller Than You Expected

When the IRS uses employer information, the refund amount stated on your original return may alter considerably.

4. You Received an IRS TREAS 310 Deposit for a Past Year

This nearly always signifies that the IRS has processed old employer data.

What To Do If You Receive a Wage-Based IRS Refund Adjustment

1. Review your transcript

It will show exactly what changed.

2. Compare employer W-2/1099 forms

Search for errors or corrected forms.

3. Wait for the official notice

CP12 or CP21A explains the adjustment.

4. Do NOT return the money

Unless the IRS directly asks restitution, the amount is valid.

5. Contact your employer if the correction seems wrong

Employers must correct W-2C inaccuracies.

Can Wage Mismatches Reduce Your Refund Too?

Yes. The IRS may reduce your refund if:

• Employer reports more income than you filed
• You underreported taxable earnings
• You claimed credits you no longer qualify for
• Your withholding was lower than reported

In some circumstances, the IRS will issue a CP21A notice and reduce your refund.

Final Summary

IRS wage mismatches are among the most typical causes of unexpected return fluctuations. When employers submit corrected wage or withholding data, the IRS:

• Recalculates your tax return
• Adjusts credit amounts
• Issues new refunds (IRS TREAS 310)
• Adds interest for late corrections
• Sends CP12 or CP21A notices afterward

These revisions frequently result in unexpected deposits, particularly for previous-year returns still being processed.

If you get an unexpected IRS TREAS 310 TAX REF or INT REF deposit, check your transcript to see if the payment was caused by a wage mismatch or an employer rectification.