IRS Notices and Letters: What Each One Means

Each row quotes what the IRS says on its “Understanding your …” page for one of 17 notices and letters, with the response timing as the IRS words it.

When we checked on November 2, 2026, each IRS page showed its own last-reviewed date; the dates are in the list of sources. Rows in each group are sorted by notice code, not by the order in which notices arrive. A row links to its own page unless the IRS page for that notice had only a few short sections.

Maintained by Archie Chang · Reviewed November 2, 2026 · Methodology & sources

Not an official source. FedRateCalc is independent and is not affiliated with the Internal Revenue Service (IRS). The notice and IRS.gov are the authority on what a notice says and asks. FedRateCalc cannot verify whether a letter is genuine, and the text inside quotation marks is quoted from IRS pages; the rest is FedRateCalc’s own wording.

Balance due and collection

Balance due and collection
Notice	What the IRS page says it is about	Response timing, as the IRS words it	Page
CP14	We sent you this notice because you owe money on unpaid taxes.	[…] Pay the amount you owe by the due date on the notice. […]	CP14 page
CP90	We intend to levy certain assets for unpaid taxes and are informing you of your right to a Collection Due Process hearing PDF.	When we checked on November 2, 2026, the IRS page “Understanding your CP90 notice” (last reviewed 06-Nov-2025) gave no response date; it says: “Read your notice carefully ― it explains our actions. […]”	CP90 page
CP501	This notice is a reminder that you owe a balance on one of your tax accounts. You received this notice because we haven't received your payment or a response to the previous notice requesting you pay this balance.	[…] Pay the amount you owe by the due date shown on the notice. […]	CP501 page
CP503	You received this notice because we haven’t heard from you and you still have an unpaid balance on one of your tax accounts.	How much time do I have?: You must pay the entire balance by the due date shown on your notice to avoid additional penalties and interest.	CP503 page
CP504	You received this notice because we haven't received payment of your unpaid balance. This notice is your Notice of Intent to Levy (Internal Revenue Code section 6331 (d)). If you don't pay the amount due immediately, the IRS can levy your income and bank accounts, as well as seize your property or your right to property including your state income tax refund to pay the amount you owe.	[…] Pay the amount you owe immediately. […]	CP504 page
CP523	If you received a CP523, CP523 (SP) or CP623 notice, the IRS is informing you of the intent to terminate your installment agreement and seize (levy) your assets. You have defaulted on your agreement.	How much time do I have?: You should contact us as soon as possible but no later than 30 days from the date of the notice.	CP523 page
LT11 / Letter 1058	We haven’t received your payment for overdue taxes. We intend to seize your property or rights to property. You must contact us immediately.	We haven’t received your payment for overdue taxes. We intend to seize your property or rights to property. You must contact us immediately.	LT11 / Letter 1058 page

IRS changes to a return or questions about it

IRS changes to a return or questions about it
Notice	What the IRS page says it is about	Response timing, as the IRS words it	Page
CP11	We corrected one or more mistakes on your tax return. As a result, the amount you owe has changed.	If you agree with the changes we made: […] Pay the amount owed by the date shown on your notice to avoid additional penalties and interest. […] If you disagree with the changes we made: […] Contact us at the number shown on the notice by the date indicated.	CP11 page
CP12	We corrected one or more mistakes on your tax return. As a result, you are now either due a refund or your original refund amount has changed.	[…] If you agree with the changes we made, no response is required. […] […] If you disagree with our changes, contact us at the number shown on the notice by the date indicated.	CP12 page
CP22A	We sent you this notice because we made the changes to your tax return. You owe because of the changes.	If you agree with the changes we made, pay the amount you owe by the date printed on your notice. Pay online now to ensure timely receipt of your payment. […] […] If you disagree with the changes we made, contact us at the number provided on your notice.	CP22A page
CP2000	The income or payment information we received from third parties, such as employers or financial institutions, doesn't match what you reported on your tax return. This difference may increase or decrease your tax or may not change it at all. […]	[…] Reply to the notice by the date listed. […]	CP2000 page

Refund applied or held

Refund applied or held
Notice	What the IRS page says it is about	Response timing, as the IRS words it	Page
CP49	We used all or part of your refund to pay a tax debt.	When we checked on November 2, 2026, the IRS page “Understanding your CP49 notice” (last reviewed 21-Jul-2026) gave no response date; it says: “[…] Pay online for a fast and secure transaction. […]”	CP49 page
CP88	We're holding your tax refund because you haven't filed one or more tax returns, and we believe you may owe taxes.	[…] File your personal tax return by the due date listed on your notice. […]	CP88 page

Return not filed

Return not filed
Notice	What the IRS page says it is about	Response timing, as the IRS words it	Page
CP59	We have no record that you filed your prior year personal tax return.	File your personal tax return immediately or explain to us why you don't need to file. […]	CP59 page

Identity verification and return review

Identity verification and return review
Notice	What the IRS page says it is about	Response timing, as the IRS words it	Page
CP05	We need more time to verify your income, income tax withholding, tax credits and/or business income. Please allow up to 60 days before reaching out.	If you filed a return: You don't need to take any action. Please do not call us until 60 days after the notice date and only if you haven't received your refund or heard from us by then. If you didn't file a return: Someone may have used your personal information to file this return. Download and complete Form 14039, Identity Theft Affidavit PDF on paper for faster service. Once you have filled out the form, sign it and mail it to the address on the top of your notice.	No separate page. When we checked on November 2, 2026, the IRS page for CP05 had only a few short sections, quoted in the FAQ.
Letter 4883C	We received a federal income tax return, Form 1040-series, filed under your Social Security number (SSN) or individual tax identification number (ITIN). To protect you from identity theft, we need you to verify your identity and the tax return so that we can continue processing it. If you didn’t file a tax return, you must let us know.	What you need to do immediately: Call the Taxpayer Protection Program Hotline shown in your 4883C letter. […]	Letter 4883C page
Letter 5071C (CP5071 series)	A federal income tax return, Form 1040 series, was filed under your Social Security number (SSN) or individual taxpayer identification number (ITIN). […]	When we checked on November 2, 2026, the IRS page “Understanding your CP5071 series notice” (last reviewed 17-Mar-2026) gave no response date; it says: “Follow the instructions on your notice to verify your identity and the tax return. […]”	Letter 5071C (CP5071 series) page

How the IRS describes billing and collection

Publication 594, The IRS Collection Process (Rev. 1-2026) says:

“You file your tax return. Most returns are filed annually (by April 15th) or quarterly (businesses with employees).
1. If you owe taxes, we will send you a bill. This is your first bill for tax due. Based on your return, we will calculate how much tax you owe, plus any interest and penalties.
2. If you don’t pay your first bill, we will send you at least one more bill. Remember, interest and penalties continue to accrue, as applicable, until you’ve paid our full amount due.
3. If you still don’t pay after you receive your final bill, we will begin collection actions. Collection actions can range from applying your subsequent tax year refunds to tax due (until paid in full) to seizing your property and assets. This could include a visit from a Revenue Officer to your home or business. Revenue officers help resolve taxes owed as part of the collection process. They tell you about your rights, obligations, options, and consequences. Unannounced visits are rare. Normally, before a visit the Revenue Officer mails an appointment letter or calls to set up a visit. See www.irs.gov/newsroom/how-to-know-if-its-really-the-irs.”

IRS Publication 594 (Rev. 1-2026), The IRS Collection Process

When we checked on November 2, 2026, the Publication 594 (Rev. 1-2026) passages in the “General steps from billing to collection” section named no notice codes, the IRS pages for CP503 and CP504 called their own notice a “second reminder” and a “final reminder”, and none of the IRS pages we collected gave a numbered list of CP notices in order. FedRateCalc therefore does not list them in an order.

Letters that claim to be from the IRS

The IRS page “Tax scams”, last reviewed October 17, 2026, says:

“If you get an email, text, letter or call that claims to be from the IRS — or if you see social media posts about how to get a big refund — it might be a scam or bad tax advice.”

IRS page “Tax scams”

“An email, call or message could be a scam if it:
Is unexpected
Rushes or threatens you
Offers refunds, credits or deductions
Pressures for personal or financial information
Tells you to pay now "or else"”

IRS page “Tax scams”

FedRateCalc cannot verify whether a letter is genuine.

Frequently asked questions

What does the IRS say about messages that claim to be from the IRS?

The IRS page “Tax scams”, last reviewed October 17, 2026, says: “An email, call or message could be a scam if it: Is unexpected Rushes or threatens you Offers refunds, credits or deductions Pressures for personal or financial information Tells you to pay now "or else"” FedRateCalc cannot verify whether a letter is genuine.

How does the IRS describe the steps from a bill to collection?

Publication 594 (Rev. 1-2026), The IRS Collection Process, says: “You file your tax return. Most returns are filed annually (by April 15th) or quarterly (businesses with employees). 1. If you owe taxes, we will send you a bill. This is your first bill for tax due. Based on your return, we will calculate how much tax you owe, plus any interest and penalties. 2. If you don’t pay your first bill, we will send you at least one more bill. Remember, interest and penalties continue to accrue, as applicable, until you’ve paid our full amount due. 3. If you still don’t pay after you receive your final bill, we will begin collection actions. Collection actions can range from applying your subsequent tax year refunds to tax due (until paid in full) to seizing your property and assets. This could include a visit from a Revenue Officer to your home or business. Revenue officers help resolve taxes owed as part of the collection process. They tell you about your rights, obligations, options, and consequences. Unannounced visits are rare. Normally, before a visit the Revenue Officer mails an appointment letter or calls to set up a visit. See www.irs.gov/newsroom/how-to-know-if-its-really-the-irs.” When we checked on November 2, 2026, the Publication 594 (Rev. 1-2026) passages in the “General steps from billing to collection” section named no notice codes.

What does the IRS say a CP05 notice means?

The IRS page for CP05, last reviewed September 25, 2026, says: “We need more time to verify your income, income tax withholding, tax credits and/or business income. Please allow up to 60 days before reaching out. If you filed a return You don't need to take any action. Please do not call us until 60 days after the notice date and only if you haven't received your refund or heard from us by then. If you didn't file a return Someone may have used your personal information to file this return. Download and complete Form 14039, Identity Theft Affidavit PDF on paper for faster service. Once you have filled out the form, sign it and mail it to the address on the top of your notice.”

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