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For you and your family
Standard mileage and other information

Forms and Instructions

Individual Tax Return
Instructions for Form 1040
Request for Taxpayer Identification Number (TIN) and Certification
Request for Transcript of Tax Return


Employee's Withholding Allowance Certificate
Employer's Quarterly Federal Tax Return
Employers engaged in a trade or business who pay compensation
Installment Agreement Request

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Amend/Fix Return
Apply for Power of Attorney
Apply for an ITIN
Rules Governing Practice before IRS

Understanding Your CP01B Notice


This notice tells you the IRS needs more information from you to process your tax return accurately.

Why we are contacting you

We received your federal income tax return; however, we need more information from you to process it. The notice you received provides two options for responding to this notice:

  1. our secure website or
  2. a toll free IRS telephone number

Both options allow you, as the taxpayer, to verify your identity and allow the IRS to continue processing your tax return.

What this process involves

The best way for you to contact us to provide the information needed to process your return is through our identity verification process described below.

What you should do

  • We highly recommend responding through our secure Identity Verification Service website. It's quick and secure. You will need to have a copy of your most recently filed tax return available to complete the entries.
  • You can also contact us using the toll free number provided in your notice. You will, again, need to have a copy of your most recently filed tax return available. Both options are available even if you haven't filed a return for this year.

How you can learn more about the IRS's identity protection efforts

The IRS is continually looking at ways to increase data security and protect taxpayers' identities. To learn more, view these topics on

Printable samples of this notice (PDF)

How to get help