Idaho State Tax Commission


CP2000 is a federal (IRS) program. It compares the income and deductions reported on your federal tax return with information reported from other sources (e.g., employers, banks, businesses). If the amounts don't match, the IRS adjusts your tax return and mails you a CP2000 notice.

What to do after getting an IRS CP2000 notice

Income and deduction amounts on your Idaho tax return must match those reported on your federal tax return unless an Idaho or federal law says otherwise.

You must contact the Tax Commission if the IRS has adjusted your federal income tax return. You must do this within 120 days of the final federal determination to avoid a negligence penalty. Interest accrues on any amount you owe, starting after the due date of the original return.

You can either:

  • File an amended Idaho individual income tax return. Attach a copy of your federal CP2000 notice and any other relevant documents.
  • Provide the Tax Commission with a copy of your federal CP2000 notice and any other relevant documents.

If you're amending a return that's beyond the three-year statute of limitations, you can only amend items directly relating to the CP2000.

Mail to:

Tax Discovery Bureau - CP2000
Idaho State Tax Commission
PO Box 36
Boise ID 83722-0410

TIP: Review your tax returns for years surrounding the CP2000 period to see if you need to make similar changes to those returns. If so, file amended tax returns for those years as soon as possible. This could help you avoid future audits.

IRS notifies Idaho

The IRS forwards information about its CP2000 audits to many states, including Idaho. This can occur years after the IRS contacts you. This is one reason why it's important to contact us promptly. If you don't file an amended return or notify us, we can adjust your return to make it match the IRS's findings at any time in the future.

Note: You might lose the ability to claim a refund if you don't amend within one year of the federal CP2000 audit notice.

How Idaho will notify you of the CP2000 adjustment

We'll mail you the Idaho CP2000 Billing Letter if you don't file an amended return. This letter gives you gives you 28 days to either pay or protest.


If you agree with Idaho's calculation of tax, you can either:

  • Pay the balance in full. See how to make payments.
  • Set up a payment plan. Sign, date, and return the Consent to Assessment (CTA) attached to the Idaho CP2000 Billing Letter. We'll mail you a bill after we receive the signed CTA.


If you don't agree with Idaho's calculation of tax, you have the right to protest. Read about CP2000 protests.

Laws and rules

Additional help

Contact us if you have questions on CP2000 audits.

Federal Filing Changes and Your Idaho Income Tax Return (01-12-2021)

If you'd like someone else to represent you during your audit, complete and return this Idaho Power of Attorney (POA) form (12-17-2019).

Page last updated January 6, 2021. Last full review of page: December 28, 2020.

This information is for general guidance only. Tax laws are complex and change regularly. We can't cover every circumstance in our guides. This guidance may not apply to your situation. Please contact us with any questions. We work to provide current and accurate information. But some information could have technical inaccuracies or typographical errors. If there's a conflict between current tax law and this information, current tax law will govern.