How to Respond to an IRS Letter (Step-by-Step Guide)

Don't panic. Most IRS letters aren't audits. In fiscal year 2024, the IRS sent roughly 220 million notices to taxpayers, and fewer than 0.4% of individual returns were selected for a substantive examination. The overwhelming majority of IRS correspondence is arithmetic — a math error, a matched 1099 that didn't tie, a payment posted to the wrong quarter, a Form 941 discrepancy for an employer.

That said: every IRS notice has a deadline, and the deadlines mean what they say. Missing a 30-day response window on a CP2000 costs you the informal appeal. Missing a 90-day window on a Statutory Notice of Deficiency costs you Tax Court jurisdiction and puts collection in motion. So the first step is not to draft a reply — it's to identify what you're holding.

Identify the notice: the code in the top-right corner is the whole story

Every IRS letter has a notice number, printed in the top-right of the first page. The prefix tells you what kind of action the IRS is taking. In descending order of urgency, these are the ones we see most often:

• LT11 / Letter 1058 — Final Notice of Intent to Levy. 30-day window to file a Collection Due Process (CDP) appeal on Form 12153. If you miss this deadline, the IRS can levy your bank accounts, wages, and receivables. This is the most time-sensitive routine notice the IRS sends.
• CP504 — Notice of Intent to Levy state refund. Precursor to LT11. Still serious but does not authorize a bank levy on its own.
• 90-day letter / Statutory Notice of Deficiency (SNOD, Letter 3219). Ninety days to petition U.S. Tax Court. If you let the 90 days lapse, the deficiency is assessed and your only remaining path is to pay first and sue for refund in district court. There is no extension of the 90 days for any reason.
• CP2000 — Underreporter Notice. 30 days to respond to the proposed changes. Not an audit — it's a computer-matching program that flags 1099s or W-2s that don't tie to your return. You can agree, partially agree, or disagree. This is where most people pay tax they don't owe because they don't push back on incorrect matching.
• CP14 — Balance Due Notice. First notice for an unpaid tax liability, usually within a few weeks of a return with a balance owed. Not urgent per se, but it starts the collection clock.
• CP11 / CP12 / CP13 — Math error notices. The IRS adjusted your return arithmetic and either raised your tax, reduced your refund, or made no dollar change. 60 days to dispute the math error before the correction becomes a full assessment subject to normal appeal rules.
• CP71A / CP71C — Annual reminder of an existing balance. Informational.
• CP2100 / CP2100A — Backup withholding notice for payers. Business-side, requires B-notice mailing to the payee.
• Letter 566 / Letter 3572 — Examination scheduling. These are the audit letters. Correspondence audit or field audit depending on complexity.

If your letter code isn't above, IRS.gov publishes a full index at irs.gov/individuals/understanding-your-irs-notice-or-letter. Type the code (e.g., CP2000) and you get the current version of that notice explained.

Read the letter carefully — the four fields that matter

Every substantive notice contains four fields you should record before doing anything else:

• Notice number (top-right, as above).
• Tax year in question. Some notices reference a year that has already been closed for statute-of-limitations purposes. Different response strategy applies.
• Response deadline. Almost always framed as a date, not a day count. Circle it.
• Amount at issue. The proposed change, the assessed balance, or the requested amount.

Also read the reason stated in the body. CP2000s in particular contain a specific list of 1099s or W-2s the IRS is trying to match — a form you already reported (sometimes reported under a different EIN or slightly different name), a form that wasn't yours at all (identity theft), or a form you genuinely missed. Which of those three is the entire response.

The deadline is real — and it's less time than it looks

The 30-day window on a CP2000 is 30 days from the date printed on the notice, not the date you received it. IRS mail is often 5 to 10 days in transit. If you got a CP2000 today with a printed date 12 days ago, you have 18 days, not 30. Two additional wrinkles:

• Foreign addresses get 60 days on most notices — 60-day windows are printed on the notice for taxpayers outside the U.S.
• Statutory Notices of Deficiency (90-day letters) get 150 days for foreign addresses. But that clock starts on the mailing date, not receipt, and does not extend for weekends or holidays.

If a deadline is genuinely impossible — you're overseas, hospitalized, or the notice was misdelivered — request an extension in writing, before the deadline, to the address on the notice. Extensions are not guaranteed, but the request itself preserves your good-faith posture and often gets an extra 30 days.

What to include in your response

For anything except a routine confirmation of an assessment, the response should include:

• The bottom tear-off of the original notice (Squarespace-scan or photocopy is fine; keep the original).
• A cover letter stating: (1) the notice number you're responding to, (2) whether you agree, partially agree, or disagree, and (3) a summary of your position in two to three sentences. Do not restate the entire tax law.
• Supporting documents — the 1099 you're contesting, the W-2 the IRS didn't have, the canceled check for a payment posted to the wrong quarter, the amended return if one is needed.
• A response form if the notice included one (CP2000, most audit notices, and 90-day letters ship with a specific reply form or petition template).
• Contact information — your daytime phone, your representative's name and CAF number if you're using one.

Two rules from years of this:

1. Never send originals. Copies only. The IRS loses documents in transit at a nonzero rate.
2. Send by certified mail with return receipt requested. For anything with a real deadline, the postmark date is your evidence of timely response.

When you can handle it yourself vs. when you need a CPA or EA

Handle it yourself if:

• It's a CP11, CP12, or CP13 math-error notice and the math is straightforward. Verify the IRS's arithmetic. If the IRS is right, sign the notice and pay (or accept the refund). If the IRS is wrong, respond within 60 days with the corrected calculation.
• It's a CP14 balance due and you agree with the balance. Pay online at IRS.gov/payments or set up an installment agreement on Form 9465 if the balance is over $10K but under $50K.
• It's a CP2000 that reflects a 1099 you genuinely forgot to include, and the resulting tax is under a few thousand dollars. Agree, sign, pay.
• It's a CP71 annual reminder. File it.

Bring in a CPA or Enrolled Agent for:

• Any 90-day letter (Statutory Notice of Deficiency). The Tax Court petition process has technical requirements and a hard deadline. Miss a filing detail and you lose jurisdiction. This is not a self-help notice.
• Any Letter 1058 / LT11 final notice of intent to levy. Collection Due Process appeals are the mechanism to preserve your rights while resolving the underlying issue. Deadlines are strict.
• Any field or office audit notice (Letter 566, Letter 3572 in-person). Preparation matters more than the audit itself. A represented taxpayer typically owes less at the end.
• Any CP2000 over $10K in proposed additional tax, or where the matched documents genuinely aren't yours, or where the mismatch involves K-1s, foreign informational reporting, or securities transactions. The IRS's cost basis on brokerage 1099s is wrong more often than it's right.
• Anything with a criminal-referral tone. Notices from the IRS Criminal Investigation Division, or letters mentioning fraud penalties, IRC Section 7201 (tax evasion) or Section 7206 (fraudulent returns) — those are not correspondence you handle in a weekend.

A CPA in good standing or an Enrolled Agent has unlimited representation rights before the IRS with a signed Form 2848 (Power of Attorney). An attorney has the same. A tax preparer without CPA/EA/attorney credentials has limited-scope representation only.

How to submit: mail, portal, or fax

For most notices, the IRS still runs on paper. The response address is printed on the notice — use that, not a general IRS address. If the notice includes a fax number, faxing is faster and gives you a same-day confirmation.

For newer notice types, the IRS is rolling out a document-upload feature at irs.gov/upload. If your notice references "Document Upload Tool" and provides an access code, use it. It's a real IRS system, and the electronic timestamp is legally sufficient. Do not confuse this with any third-party "IRS response portal" — the only official IRS upload channel is on irs.gov.

Follow-up: expect silence, then a resolution letter

After you respond, expect no acknowledgment for 30 to 90 days. Do not call the IRS in the interim; the phone agent generally cannot see correspondence in process. If you have not received a response by day 120, then call — the general IRS taxpayer assistance line is 800-829-1040, and the account tax representative can confirm the notice status.

The resolution letter will either accept your response (case closed, no further action), reject your response (moves to the next stage — often Appeals), or request additional information (30-day window opens again). Repeat the process until it closes.

And — worth saying plainly — most cases close in the taxpayer's favor when the response is timely, complete, and technically correct. The system genuinely works. The people who lose are the people who ignore the letter, or the people who reply emotionally rather than substantively.

If your notice is complex — or if you've received two on the same tax year, which is often a sign the IRS is moving toward examination — that's a conversation worth having.

David Meyer, CPA is a Partner at Laléa & Black and leads the firm's taxation practice, including IRS controversy and examination representation for individuals, closely held businesses, and trusts.