IRS Notices Explained
Understanding IRS Audit Letters, CP Notices, and Examination Correspondence
Receiving a letter from the Internal Revenue Service can be stressful, particularly if you are unsure why the notice was issued or what action is required. Some IRS notices simply request additional information, while others notify taxpayers of an audit, propose adjustments to a tax return, request supporting documentation, or explain appeal rights.
This resource center explains many of the most common IRS notices and audit-related letters. Our goal is to help taxpayers understand what each notice generally means, what deadlines may apply, and where the notice fits within the overall IRS examination process.
Whether you have received a CP notice, an IRS audit letter, an Information Document Request, or a Notice of Deficiency, understanding the purpose of the correspondence is an important first step toward responding appropriately.
Key Takeaways
- IRS notices serve many different purposes and should not be ignored.
- Some notices request information, while others begin or continue an IRS audit.
- Many IRS notices contain important response deadlines.
- Understanding why the notice was issued often determines the appropriate next step.
- This guide links to detailed explanations of the most common IRS notices and examination letters.
Types of IRS Notices
The IRS issues thousands of different notices each year. Some relate to return processing, others involve collections, and many are associated with examinations or audits. The resources below focus primarily on notices taxpayers may receive during the IRS audit process.
Audit Notification Letters
Letters informing taxpayers that an examination has been initiated and explaining how the audit will proceed.
Information Requests
Correspondence requesting records, books, receipts, or other documentation supporting the tax return.
Proposed Adjustments
Letters explaining changes the IRS proposes to make following its review of the return.
Appeal & Closing Letters
Notices explaining appeal rights, closing an examination, or outlining the next procedural step.
IRS Audit Notice and Letter Directory
Use the notice or letter number shown near the top of your IRS correspondence to locate the most relevant guide below. Some IRS letters begin an examination, some request documentation, and others explain proposed adjustments, appeal rights, or deadlines. The exact response required depends on the letter received and the facts of the case.
Start With the Number on Your Letter
Look for a notice or letter number such as CP2000, Letter 525, Letter 915, or Letter 3219. It is usually printed near the upper-right corner or near the date of the correspondence.
Return Review and Pre-Audit Notices
These notices may identify differences in reported information or request documentation before the matter develops into a broader examination.
CP2000 — Proposed Changes for Underreported Income
A CP2000 generally identifies a mismatch between information reported to the IRS by third parties and the information shown on the taxpayer's return.
Read the CP2000 guide →CP2501 — Request for Information
This notice may request clarification about information-reporting differences before the IRS determines whether to propose an adjustment.
Guide coming soonCP75 Series — Refund or Credit Examination
CP75-series notices commonly advise that the IRS is examining one or more credits or claimed items and needs supporting documentation.
Guide coming soonAudit Notification and Appointment Letters
These letters generally notify the taxpayer that a return has been selected for examination or provide instructions for scheduling and beginning the audit.
Initial Contact Letters
Initial examination correspondence generally identifies the return under review, the issues being questioned, and the records the IRS wants the taxpayer to provide.
Overview guide coming soonLetter 2202-B or Letter 566-S
These letters may be used in correspondence examinations to identify the items being audited and request supporting documentation.
Guide coming soonLetter 3572-A — Office Audit Appointment
This letter may ask a corporation or partnership taxpayer to contact the IRS to arrange an initial office-examination appointment.
Guide coming soonLetter 2205-D — BBA Partnership Examination
This letter notifies certain partnerships that a return has been selected for examination under the centralized partnership audit regime.
Guide coming soonDocument and Information Requests
During an examination, the IRS may request records, written explanations, accounting information, and other materials needed to evaluate the return.
Form 4564 — Information Document Request
Form 4564 is commonly used during an examination to request specific books, records, documents, schedules, or written explanations.
Read the IDR guide →Supporting-Document Requests
Audit letters may request receipts, bank statements, mileage logs, accounting reports, basis records, or other documentation supporting the return.
Review the recordkeeping guide →Proposed Adjustment and 30-Day Letters
These letters commonly accompany examination reports and explain proposed changes, response options, and possible administrative appeal rights.
Letter 525 — General 30-Day Letter
Letter 525 generally transmits proposed examination adjustments and explains how the taxpayer may respond or request administrative review.
Read the Letter 525 guide →Letter 915 — Examination Report Transmittal
Letter 915 is another 30-day letter used to transmit proposed audit adjustments and explain available response options.
Read the Letter 915 guide →Revenue Agent Report
The examination report generally summarizes the proposed adjustments, the tax effect, and the examiner's explanation of the issues.
Guide coming soonAppeals Rights Following an Audit
When appeal rights are available, the taxpayer may have a limited period to submit a protest or request review by the IRS Independent Office of Appeals.
Review the Appeals guide →Statutory Notices and Tax Court Deadlines
Statutory notices can carry strict legal deadlines. Taxpayers should read these notices carefully and avoid assuming that ordinary correspondence deadlines apply.
Letter 3219 — Notice of Deficiency
A Notice of Deficiency, often called a 90-day letter, advises that the IRS proposes a deficiency and explains the deadline for filing a petition with the United States Tax Court.
Read the Notice of Deficiency guide →CP3219 Series
Certain CP3219 notices serve as statutory notices of deficiency and may include a Tax Court petition deadline.
Guide coming soonAudit Closing Letters
Closing correspondence may advise that the audit resulted in no change, that an agreement was accepted, or that the examination has otherwise been concluded.
No-Change Letter
A no-change letter generally confirms that the IRS accepted the return as filed for the issues examined.
Guide coming soonAgreed Examination Closing Letter
This correspondence may confirm that the examination is closing based on agreed adjustments or other completed actions.
Guide coming soonWhat Should You Do After Receiving an IRS Notice?
The correct response depends on the notice received, the tax year involved, and the action the IRS is proposing. Some notices can be resolved by providing a missing document or correcting an information mismatch. Others may begin an audit, request extensive records, propose additional tax, or establish a deadline for requesting Appeals review or filing a Tax Court petition.
Before responding, identify the notice or letter number, determine what the IRS is requesting, and locate the response deadline. Avoid assuming that every IRS letter requires the same type of response.
Confirm the Notice Is Authentic
Review the taxpayer name, tax year, notice number, IRS contact information, and the reason stated for the correspondence. Be cautious about telephone calls, emails, or text messages claiming to be from the IRS.
Identify the Notice or Letter Number
The number printed on the correspondence often provides the fastest way to understand the purpose of the letter and the procedural stage of the matter.
Determine What the IRS Is Requesting
The IRS may be asking for payment, documentation, clarification, agreement with proposed changes, a signed response, or a formal protest. Read the entire notice rather than relying only on the heading.
Record the Deadline
Some deadlines are administrative, while others may affect legal rights. A 30-day response period, a document-production deadline, and a Tax Court petition deadline are not interchangeable.
Gather the Relevant Records
Collect the return, supporting records, prior correspondence, information statements, and any documentation directly related to the issue identified in the notice.
Decide Whether Professional Assistance Is Appropriate
Professional assistance may be appropriate when the notice begins an audit, involves substantial proposed tax, requests business records, contains appeal rights, or creates uncertainty about the correct response.
Match the Response to the Type of Notice
IRS correspondence should be evaluated based on what the notice actually does. The following framework provides a general starting point.
| Type of Notice | Typical Purpose | Possible Next Step |
|---|---|---|
| Information mismatch | Compares the return with third-party information. | Review the data and agree or respond with corrections and supporting records. |
| Audit opening letter | Begins a correspondence, office, or field examination. | Identify the issues, deadlines, examiner, and requested records. |
| Information Document Request | Requests specific documents, explanations, or accounting information. | Prepare an organized response matched to each request. |
| Proposed adjustment or 30-day letter | Explains proposed audit changes and possible Appeals rights. | Review the findings and determine whether to agree, respond, or request Appeals review. |
| Notice of Deficiency | Provides formal notice of a proposed deficiency and a Tax Court petition deadline. | Evaluate the deadline and available judicial or administrative options immediately. |
| Closing letter | Confirms the result or closure of the examination. | Retain the letter with the tax records and confirm any remaining obligations. |
IRS Notice Deadlines Matter
Many IRS notices include a date by which the taxpayer must respond. Missing that date may lead to proposed adjustments, loss of administrative review opportunities, assessment of additional tax, or expiration of a court filing deadline.
Not every deadline has the same legal effect. A deadline for submitting receipts may sometimes be extended through communication with the examiner, while a statutory Tax Court deadline generally requires strict compliance.
When a notice includes appeal rights, a Notice of Deficiency, or another significant procedural deadline, prompt review is especially important.
Common Mistakes After Receiving an IRS Notice
Ignoring the Letter
IRS matters generally continue even when the taxpayer does not respond.
Assuming the IRS Is Correct
IRS notices may be based on incomplete, duplicated, or misunderstood information and should be reviewed carefully.
Sending Unorganized Records
Documents should be matched to the issues and requests identified in the notice whenever possible.
Responding to the Wrong Issue
A response may be ineffective when it does not directly address the adjustment, discrepancy, or documentation request described by the IRS.
Missing the Deadline
Waiting too long can reduce the available administrative or judicial options.
Calling Without Preparation
Before contacting the IRS, review the return, notice, timeline, and relevant records so the discussion remains accurate and focused.
Where an IRS Notice May Fit in the Audit Process
Not every audit follows this exact sequence, but many examination matters move through several of these stages.
Practical Considerations
One of the most common mistakes taxpayers make is reacting to the amount shown on an IRS notice before understanding how the IRS calculated it. The first step should usually be identifying the type of notice, reviewing the underlying return, and determining whether the IRS used complete and accurate information.
Another common misunderstanding is assuming that every IRS letter begins a full audit. Some notices involve automated information matching, while others are part of a formal examination. The response strategy should match the actual procedure involved.
The notice number, deadline, tax year, proposed action, and supporting explanation usually provide the starting point for determining the appropriate response.
Frequently Asked Questions
Does every IRS notice mean I am being audited?
No. Some notices involve automated processing, missing information, information-return mismatches, payment issues, or other matters that are not formal audits.
Where can I find the notice or letter number?
The notice or letter number is commonly printed near the date, in the upper-right portion of the letter, or within the identifying information on the first page.
Should I call the IRS immediately?
Before calling, review the notice, the relevant tax return, and the supporting records so you understand the issue and can communicate accurately.
What if I agree with the IRS notice?
Follow the instructions in the notice regarding agreement, payment, signatures, or other required actions. Retain a copy of the response and supporting correspondence.
What if I disagree with the IRS notice?
Review the stated reason for the adjustment and respond with a clear explanation and supporting documentation when appropriate. Some notices also explain administrative appeal rights.
Can a CPA respond to an IRS notice for me?
With proper authorization, a CPA may communicate with the IRS, review the notice, organize documentation, and assist with the response.
What if the deadline has already passed?
Available options depend on the type of notice, how much time has passed, and whether tax has already been assessed. Prompt review is important.
Should I send original documents?
Taxpayers generally retain original records and provide copies unless the IRS specifically requests otherwise.
Received an IRS Notice?
The notice number, response deadline, tax year, and proposed IRS action determine what should happen next. If the letter involves an audit, Information Document Request, proposed adjustment, appeal right, or significant deadline, careful review can help protect your options.
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