Quick overview

A correspondence audit is the IRS’s way of resolving small discrepancies without an in-person office or field visit. The IRS sends a letter that identifies the item(s) in question—common examples include mismatched income (W-2/1099), questioned deductions, or credits—and asks you to mail supporting documentation. These audits are the most common type of IRS exam and are generally narrow in scope (IRS, Publication 556).

Why you might get a correspondence audit

The IRS selects returns for correspondence audits when automated systems or third-party reporting (like Forms W-2 and 1099) don’t match what taxpayers reported, or when a return includes unusual or high-value deductions that trigger a review. Other triggers include math errors, missing schedules, or information received after a return was processed (see: What Triggers an IRS Correspondence Audit). In my practice working with small-business owners and freelancers, mismatched 1099 income and large business-expense lines are the most frequent reasons clients receive these letters.

Typical timeline — what to expect and when

  • Notice issued: The IRS mails a notice with a return address and a deadline. Most correspondence audit letters give 30 days to respond from the date on the letter. Some notices (especially those that propose an adjustment) may allow 60 days to appeal. (IRS notice guidance; Pub. 556.)
  • Your initial response: Aim to respond within 14–21 days if you can; this creates buffer time for follow-up. In my experience, early responses tend to shorten the overall resolution time.
  • IRS review: After the IRS receives your package, expect 6–12 weeks for them to process and respond, depending on mail volume and the examiner’s queue. If they need more, they’ll send another letter.
  • Final determination: Most correspondence audits close within 60–180 days from the notice date—shorter if documentation is clear and complete; longer if the IRS requests more evidence or refers the case for further review.

Timelines vary by case. If you miss a deadline, the IRS can make an assessment based on available information, which typically increases tax owed and may add penalties and interest.

Step-by-step: How to respond (practical checklist)

  1. Read the notice carefully. Note the letter ID (e.g., CP2000 or other IRS letter number), the tax year affected, the items in question, and the response deadline.
  2. Verify authenticity. Confirm the letter is from the IRS—real IRS letters include an IRS logo, a contact phone number, and usually a request to return documentation by mail. If you’re unsure, compare details at irs.gov or call the number printed on the letter. Beware of scams; the IRS will not demand immediate payment by unusual methods (IRS Consumer Alerts).
  3. Gather documents that directly support the line items in question. Typical evidence includes:
  • Income: Forms W-2, 1099s, bank deposit records, year-end statements.
  • Deductions: Receipts, invoices, cancelled checks, mileage logs, proof of business purpose.
  • Credits: Childcare receipts, education statements (Form 1098-T), adoption records, etc.
  1. Prepare a concise cover letter. Explain each document and connect it to the line item. Numbering your exhibits to match the IRS’s list makes the examiner’s job easier.
  2. Make and keep copies. Send copies, not originals, unless the IRS specifically asks for an original.
  3. Mail securely and get proof of delivery. Use certified mail with return receipt or another trackable service. Keep all tracking info.
  4. Consider professional representation. If the issue is complex, sign a Form 2848 (Power of Attorney) so a CPA, enrolled agent, or attorney can communicate with the IRS on your behalf.

Evidence that persuades examiners

The IRS looks for contemporaneous, verifiable records that substantiate your claim. The most persuasive evidence is:

  • Original receipts and invoices showing date, amount, vendor, and business purpose.
  • Bank or credit card statements that corroborate payments (highlight relevant transactions).
  • Contracts, signed client letters, or correspondence that prove income or services rendered.
  • Detailed mileage logs that show dates, destinations, and business purpose for vehicle deductions.

If you lack ideal records, look for reasonable substitutes: bank statements, client emails confirming work and payment, or appointment logs. The IRS accepts alternative documentation when original receipts are unavailable, but you need to explain why originals are missing and supply corroborating evidence (see: Understanding Alternative Documentation for Tax Deductions During an Audit).

Common letters you might receive

  • CP2000: Proposed changes because reported income doesn’t match third-party data. This is not an audit notice in the strictest sense but can lead to an audit if ignored.
  • Standard correspondence audit letters: These will reference a letter number and list what the IRS needs. Always follow the instructions on the letter exactly.

Possible outcomes

  • No change: Your documents fully support the return and IRS accepts them.
  • Adjustment: IRS proposes additional tax owed; you can pay, arrange a payment plan, or contest the finding.
  • Further examination: If the issue is broader than the items reviewed, the IRS might escalate to an office or field audit.

If you disagree: appeals and next steps

If you disagree with the IRS’s determination after a correspondence audit, you can request an appeal with the IRS Office of Appeals. You also have the right to seek help from the Taxpayer Advocate Service if the process creates a hardship or if the IRS did not follow proper procedures (Taxpayer Advocate Service, IRS.gov). If a significant tax is at stake, consult a tax attorney or CPA about filing a formal protest.

Real-world tips from practice

  • Be proactive. When I represent clients, I prepare a one-page summary tying each piece of evidence to the tax return line. Examiners appreciate concise organization.
  • Don’t overshare. Send only the documents the IRS requests plus directly related backups. Adding unrelated paperwork can confuse the review.
  • Track communications. Log every call, letter, and submission. Note dates, names, and badge numbers for any IRS agent you speak with.

Preventive recordkeeping

Keep records for at least three years after filing—the IRS can generally audit returns filed within three years, though certain situations (substantial omission of income) extend that window to six years (IRS guidelines). Maintain organized files: digital copies, scanned receipts, and a simple index make responses faster. For small businesses, a separate business bank account and integrated bookkeeping reduce audit risk and simplify responses.

Scam warning and authenticity checks

Scammers often mimic IRS letters. Real IRS correspondence will reference your tax return details, provide a way to respond, and will not demand payment by gift card or threaten immediate arrest. If you suspect a scam, verify by visiting irs.gov or calling the IRS directly using the contact info on the official site (IRS Consumer Alerts).

Useful internal resources

When to get professional help

If the proposed change would increase tax owed substantially, if the records are incomplete, or if you’re unsure how to respond, engage a qualified tax pro. In my 15 years working with taxpayers, early professional involvement often reduces proposed adjustments and prevents escalation.

Conclusion and practical next steps

When you receive an IRS correspondence audit letter:

  1. Read and authenticate the notice.
  2. Gather focused documentation tied to the IRS’s questions.
  3. Send a clear, organized response with copies and proof of delivery.
  4. Consider having a tax professional represent you if complexity or risk is high.

Professional disclaimer: This article is educational and not individualized tax advice. For advice tailored to your situation, consult a CPA, enrolled agent, or tax attorney. Authoritative sources include IRS Publication 556 and IRS guidance on notices and audits (irs.gov, 2025).