Backup Withholding on 1099-NEC: Box 4 Explained [2026 Guide]

See an amount in Box 4 of your 1099-NEC? This guide explains what backup withholding is, why it happened, and how to claim credit or stop it from continuing.

What is Box 4? Backup withholding (Box 4) is a 24% federal tax that businesses withhold from contractor payments when the contractor hasn't provided a valid TIN, or when the IRS notifies the payer of issues with the contractor's tax reporting.

What Triggers Backup Withholding?

Payers must begin backup withholding when any of the following occur:

• Contractor didn't provide TIN: The W-9 was not submitted or the TIN field was left blank.
• IRS notified TIN is incorrect: A B-Notice from the IRS states that the name and TIN combination doesn't match their records.
• IRS notified contractor underreported: A C-Notice indicates the contractor has a history of not reporting income.
• Contractor didn't certify exempt status: The contractor failed to certify they're not subject to backup withholding on their Form W-9.

The 24% Withholding Rate

When backup withholding is triggered, the payer must withhold a flat 24% from the contractor's payment and remit it to the IRS.

Example Calculation:

• Payment to contractor: $5,000
• Backup withholding (24%): -$1,200
• Net payment to contractor: $3,800

The payer reports $5,000 in Box 1 (total nonemployee compensation) and $1,200 in Box 4 (federal income tax withheld). The contractor only received $3,800 in their bank account, but they are taxed on the full $5,000 gross amount.

How to Report Backup Withholding

For Payers (Businesses)

1. Enter the withheld amount in 1099-NEC Box 4.
2. File Form 945 with the total backup withholding for the year.
3. Deposit withheld taxes according to the IRS deposit schedule.
4. Ensure Form 945 is filed by the January 31 deadline.

For Recipients (Contractors)

1. Locate the amount in your 1099-NEC Box 4.
2. Enter this amount on Form 1040, Line 25b.
3. This amount counts as tax you have already paid to the IRS.
4. It directly reduces the total tax you owe or increases your tax refund.

The W-9 Connection

Form W-9 prevents backup withholding. When a contractor properly completes and signs a W-9, they provide:

• Their correct TIN (SSN or EIN)
• Certification that the TIN is correct
• Certification that they are not subject to backup withholding

Best practice: Always collect a signed W-9 before making the first payment to any contractor. This protects your business from liability and prevents withholding headaches later.

How to Stop Backup Withholding

If backup withholding is currently being applied to your payments, here are the steps to stop it:

1. Obtain your correct TIN: Get your Social Security card or EIN confirmation letter from the IRS to verify your exact details.
2. Complete a new W-9: Fill out Form W-9 with the correct, matching information.
3. Certify your status: Sign Part II certifying you're not subject to backup withholding (if true).
4. Submit to payer: Give the corrected W-9 to the business that is withholding your pay.
5. Resolve IRS issues: If the IRS sent a notice, resolve the underlying issue directly with them (e.g., file missing tax returns or pay outstanding balances).

Understanding B-Notices and C-Notices

B-Notice (CP2100/CP2100A)

A B-Notice means the IRS found that the name and TIN you reported on a 1099 do not match their database records.

• Response: Contact the contractor immediately for a corrected W-9. You must begin backup withholding if the information is not corrected within a reasonable time (usually 30 business days).

C-Notice

A C-Notice means the IRS determined the payee underreported their income (they didn't report previous 1099 payments on their tax return).

• Response: Begin backup withholding immediately. You must continue withholding 24% until the IRS explicitly notifies you to stop.

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Frequently Asked Questions

What is backup withholding?

Backup withholding is a federal tax withholding of 24% that businesses must take from payments to contractors in certain situations. It's called 'backup' because it backs up the income tax system when the IRS can't properly track income to a taxpayer.

What triggers backup withholding on 1099-NEC?

Backup withholding is triggered when: (1) The contractor didn't provide a TIN (SSN or EIN), (2) The IRS notifies you the TIN is incorrect (B-Notice), (3) The IRS says the contractor underreported income (C-Notice), or (4) The contractor didn't properly certify on Form W-9.

What is the backup withholding rate?

The current backup withholding rate is 24% of the payment. So if you pay a contractor $1,000 and backup withholding applies, you withhold $240 and pay them $760. You then remit the $240 to the IRS.

How do I report backup withholding as a payer?

Enter the amount withheld in Box 4 of Form 1099-NEC. Report and pay the total backup withholding to the IRS using Form 945 (Annual Return of Withheld Federal Income Tax). Form 945 is due January 31 of the following year.

How do contractors claim credit for backup withholding?

Contractors report backup withholding as federal income tax withheld on their Form 1040, line 25b. The amount appears in Box 4 of their 1099-NEC. It counts as a tax payment and reduces their tax owed (or increases their refund).

How do I stop backup withholding?

Provide the payer with a correct W-9 with your accurate TIN and sign the certification that you're not subject to backup withholding. If the IRS sent a notice, resolve the underlying issue (correct TIN mismatch, file missing returns, report missing income).

What is a B-Notice and C-Notice?

A B-Notice (CP2100/CP2100A) means the IRS found a TIN/name mismatch in your filing. A C-Notice means the IRS determined the payee underreported income. When you receive these, you must begin backup withholding on future payments to that contractor until resolved.

Is backup withholding the same as regular tax withholding?

No. Regular tax withholding (like on W-2 wages) is based on the employee's W-4 and varies by income and exemptions. Backup withholding is a flat 24% applied in specific situations when the IRS can't properly track income. It's not based on the recipient's tax situation.

Prevent Backup Withholding Issues

Collect W-9 forms from all contractors before payment. Our 1099-NEC generator helps you stay compliant and avoid withholding surprises.

• Generate 1099-NEC
• W-9 Generator

Related Resources

• 1099-NEC Generator - Create 1099-NEC forms with Box 4.
• W-9 Generator - Collect contractor information.
• Nonemployee Compensation - Understanding 1099-NEC Box 1.
• 1099-NEC Threshold - When to file 1099-NEC.
• How to Correct 1099-NEC - Fix mistakes on filed forms.
• 1099-NEC for Small Business - Complete filing guide.