Understanding Your CP01B Notice

What this notice is about

We received your federal income tax return and need more information from you to process it accurately.

What you need to do

If you filed a tax return or didn't file a tax return

Contact us online or by phone to verify your identity and tax return information.


  • Use our secure Identity Verification Service. It's quick, secure, and available 24 hours a day.
  • Have a copy of the CP01B notice you received and a copy of the tax return for the tax year shown in the notice.

By phone

  • Call the toll-free IRS Identity Verification telephone number in the CP01B notice.

If we can't verify your identity over the phone or online, we may ask you to schedule an appointment at your local IRS office to verify your identity in person.

Note: Authorized third parties may help taxpayers, but the taxpayer must be present on the phone or in person.

If we don't hear from you, we won't be able to process your return, issue refunds, or apply overpayments to next year's estimated tax.

Note: The toll-free number IRS Identity Verification number is for identity verification only. It's not for other tax-related information, including refund status.

Frequently asked questions

What happens after I verify online or after I call?

We'll continue processing your return. It will take about nine weeks to process.

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