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In the IRS’s own words · not reviewed by VALID

CP310 notice explained, in the IRS’s own words

We assigned you a Personal Identification Number (PIN) to associate your existing Centralized Authorization File (CAF) number through Tax Pro Account for identity assurance.

Read the full CP310 page on irs.gov ↗

Quoted from www.irs.gov/individuals/understanding-your-cp310-notice, read October 15, 2026 · fingerprint f15354eefd9f

What this notice is about

We assigned you a Personal Identification Number (PIN) to associate your existing Centralized Authorization File (CAF) number through Tax Pro Account for identity assurance.

You don't need to call or respond to this notice.

What you need to do with the PIN

Use the PIN number to verify your identity and complete your request:

  • Sign in to Tax Pro Account.
  • Associate your CAF number to your personal information by entering your PIN.

You may want to

  • Keep your PIN in a safe place for your records.
  • Call the IRS number at the top of your notice if you didn't request a PIN or if you have questions.

Important things to remember about your PIN

  • It can only be used to verify ownership of your CAF number in Tax Pro Account and will expire in 30 days.
  • It is unique to your CAF number.
  • It is for your use only. Keep it secure and don't share it with anyone.

What to do next

  • Write down the date on the letter today.
  • Look the number up on irs.gov yourself. Don’t trust a link or phone number from anyone else.
  • If it says you owe money or proposes changes to your return, take it to a licensed CPA, EA or tax attorney before that date.

Not advice. Not a filing. Verify with a licensed professional. Rules change by year and facts.

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