Overview

A correspondence audit (sometimes called a letter audit) is the IRS’s most common, low‑intensity audit: it asks for specific documents or clarifications by mail rather than scheduling a field or office visit. These audits focus narrowly on items that don’t match IRS records or that look unusual on their face. Most are resolved by sending supporting documents and a short cover letter. (See IRS Publication 556 for how examinations work: https://www.irs.gov/pub/irs-pdf/p556.pdf.)

In my 15+ years advising taxpayers, I’ve found that a calm, organized response and good recordkeeping usually resolves correspondence audits without additional assessments. This article walks through common triggers, how the letter will look, step‑by‑step response actions, documentation checklist, timing, when to hire a pro, and next steps if you disagree with the IRS.

Common triggers for correspondence audits

  • Income mismatches: The IRS cross‑checks forms it gets from payers (W‑2s, 1099‑NEC, 1099‑MISC, 1099‑B, 1099‑DIV, 1099‑INT, SSA earnings) with what you reported. Any mismatch—missing a 1099, different amounts—often generates a letter.

  • Unusually large or out‑of‑pattern deductions and credits: Deductions or credits that differ materially from taxpayers with similar incomes draw attention (e.g., very large business expenses, large charitable deductions with little documented giving, or high unreimbursed employee expenses).

  • Math, formatting, or clerical errors: Transposition errors, missing schedules, or incorrect Social Security numbers can trigger review.

  • Unreported income from third parties: If a payer reports income and you don’t claim it (even by accident), the IRS will typically send a notice asking you to explain the discrepancy or pay the tax due.

  • Information returns flagged for review: Items like stock sales on 1099‑B, cancellation of debt, or certain credits (EITC) undergo closer review.

  • Random selection and compliance checks: Some correspondence audits are automated compliance checks to verify specific return items.

These triggers align with IRS enforcement practices and the agency’s intent to resolve simple discrepancies efficiently (IRS, Examination of Returns, Publication 556).

How the IRS letter looks and what it asks

IRS correspondence letters are specific. They will:

  • Quote the tax year and identify the return line or code being questioned.
  • State a deadline to respond (the exact time frame is printed on the letter; it is commonly 30 days but may vary). Always use the deadline on the notice—do not assume a universal timeframe.
  • Give a mailing address or instructions for submitting documents. Some notices allow fax or secure upload; follow the letter’s directions.
  • Offer a contact phone number. If you call, have the notice and supporting documents at hand.

Never ignore the letter. Nonresponse typically results in the IRS making a change to your return (often an assessment of tax due) and sending a bill.

Step‑by‑step: How to respond to a correspondence audit

  1. Read the letter carefully and note the deadline. Confirm whether the IRS requests copies of documents or a signed statement. Don’t guess—follow the instructions verbatim.

  2. Do not send original documents. Send clear, legible photocopies unless the IRS specifically asks for an original.

  3. Gather the exact documents the IRS requests and any supporting records that explain the amounts on your return: W‑2s, 1099s, business receipts, invoices, bank statements, canceled checks, worksheets, mileage logs, and signed contracts.

  4. Create a short cover letter that:

  • References the notice number and tax year.
  • Lists the enclosed documents with brief explanations.
  • States your requested outcome (for example, “Please accept these documents verifying the business expenses reported on Schedule C.”)

  1. Organize the packet with a clear table of contents and label tabs or PDF bookmarks if submitting electronically. Start with a copy of the original return and a copy of the IRS notice.

  2. If you disagree with the IRS position, include a concise explanation and any evidence to support your position. Identify calculations and cite tax code or authoritative guidance if applicable (having a tax professional prepare this helps).

  3. Mail via certified mail with return receipt or use the IRS secure portal/fax option listed on the notice. Keep a copy of everything sent and notes of any phone calls.

  4. Track response timelines. If you need more time, contact the number on the notice as soon as possible to request an extension; do this before the deadline.

In my practice, sending a well‑organized packet within the deadline and following up by phone when reasonable resolves the majority of cases.

Documentation checklist (what to include)

  • Copy of the IRS notice and the tax return in question.
  • Forms showing income reported to the IRS (W‑2, 1099s).
  • Receipts, invoices, contracts, bank statements, canceled checks, and credit‑card statements to substantiate expenses.
  • Mileage logs and calendars for business travel or medical appointments.
  • Bank deposit slips or ledgers to show income deposits that match reported amounts.
  • Signed statements (if requested) from third parties or corroborating witnesses.

For a printable, step‑by‑step packet checklist, see our guide on Preparing a Response Package for an IRS Correspondence Audit: https://finhelp.io/glossary/preparing-a-response-package-for-an-irs-correspondence-audit/.

Also review the timeline and required documents in Preparing for a Correspondence Audit: Documents and Timelines: https://finhelp.io/glossary/preparing-for-a-correspondence-audit-documents-and-timelines/.

Common mistakes to avoid

  • Sending originals: The IRS generally requests copies; originals can be lost.
  • Over‑explaining without evidence: Stick to facts and supporting documents; long narratives without proof slow review.
  • Missing the deadline: Late replies may lead to automatic adjustments and penalties.
  • Providing incomplete documentation: Don’t expect the IRS to infer—show the link between the document and the return line.
  • Assuming silence equals resolution: If you never receive a closing letter, follow up.

Timelines, penalties, and interest

The notice will give the specific response timeframe. If the IRS assesses additional tax because you failed to respond, you may owe tax, interest, and penalties. Interest runs from the original due date of the return; penalties depend on the issue (e.g., accuracy‑related penalty). For appeals and examination rights, see IRS Publication 556 (Examination of Returns) and the appeals section on IRS.gov.

When to hire a tax professional or attorney

Hire a CPA, enrolled agent (EA), or tax attorney when:

  • You are uncomfortable communicating with the IRS.
  • The dollar amount at issue is large or could lead to penalties.
  • The request involves complex issues (e.g., business losses, self‑employment, or foreign accounts).
  • You prefer representation—an enrolled agent or attorney can represent you and communicate directly with the IRS.

A professional helps assemble stronger evidence and crafts legal arguments when needed. In my experience, a professional responder reduces the chance of unnecessary adjustments and speeds resolution.

If you disagree with the IRS decision

If the IRS makes a change after you respond and you disagree, you generally have administrative appeals rights. The notice you receive after an adjustment explains appeal options, and you may request an appeals conference. Our guide on Appeals Options After an Audit Adjustment explains the administrative remedies: https://finhelp.io/glossary/appeals-options-after-an-audit-adjustment-administrative-remedies/.

Recordkeeping: how long to keep records

Keep supporting documents for at least three years from the date you filed the return (the typical statute of limitations). Keep records longer if you:

  • Underreported income by more than 25%: keep for six years.
  • Filed a fraudulent return: indefinite until resolved.
  • Filed a claim for credit or refund: at least three years from filing or two years from tax paid, whichever is later.

For practical recordkeeping strategies, see our article on Recordkeeping Best Practices to Survive an IRS Audit: https://finhelp.io/glossary/recordkeeping-best-practices-to-survive-an-irs-audit/.

Final practical tips

  • Respond quickly and professionally. A short packet that directly answers the IRS’s numbered questions is better than a large, disorganized bundle.
  • Keep copies of everything. Proof of delivery matters.
  • Use plain language in your cover letter and label documents so an IRS examiner can find supporting evidence fast.
  • If you call the IRS, take notes: agent name, badge number, date, and summary of the call.

Professional disclaimer: This article is educational and general in nature and does not constitute tax, financial, or legal advice. For advice tailored to your facts, consult a licensed tax professional.

Authoritative sources

Internal resources (FinHelp)

If you want, I can create a printable response packet template and a sample cover letter tailored to a common income mismatch scenario.