IRS Audit by Mail: How to Handle a Correspondence Audit

An IRS examination that arrives in your mailbox rather than as a knock on your door is what we call a correspondence audit, and it is the kind I field most weeks at my desk here in Manhattan. Here is the irs correspondence audit explained the way I explain it to a new client across the table. The IRS computer flags one or two line items on your return. Instead of sending an agent to your office, the Service mails you a letter that asks you to back up those items with paper. You answer by mail or by fax. A reviewer in a service center reads your response, and the case closes. No conference room, no field visit, no agent walking through your books. The whole thing lives in envelopes, which is exactly why it tends to feel scarier than it really is.

This is the most common audit type by a wide margin. Roughly three out of four individual examinations the IRS runs are handled this way, because mail is cheap and the items in question are narrow. A correspondence audit almost never looks at your entire return. It zeroes in on something specific. A charitable deduction that looks large against your income. A Schedule C with heavy expenses. A dependent that two people claimed. Wages that do not match what an employer reported to the government. The notice tells you exactly which item is in question and which tax year, so you are never guessing about what the Service wants.

The mechanics start with a letter. Common ones include the CP2000 underreporter notice, which proposes more tax because a 1099 or W-2 in the IRS system did not show up on your return. You may also see a Letter 566, the general examination letter, or a CP75 notice tied to the Earned Income Tax Credit. Each one names a deadline, usually thirty days, and lists the documents the reviewer wants to see. The letter also gives you a fax number and a mailing address, and you get to pick which one you use.

Here is a worked example from this past spring. A graphic designer in Brooklyn earned 9,400 dollars from a client who filed a 1099-NEC. She forgot the form and left that income off her return. Eight months later a CP2000 landed, proposing about 2,600 dollars in tax plus interest. We pulled her bank records, confirmed the income was real, but then found 3,100 dollars of home-office and software costs she never deducted against that job. We responded by mail, agreed to the income, and attached the offsetting expenses. Her final bill dropped to under 900 dollars. The letter that looked like a 2,600 dollar problem became a 900 dollar one because we read it as a starting point, not a sentence.

The mistake we see every year is people reading the proposed number as a final bill and either panicking or paying it without a second look. It is a proposal, not a verdict. You have the right to disagree and send documents, and that right does not expire until the deadline on the letter does. The other edge case worth flagging is that a correspondence audit can quietly expand. If your mailed answer raises new questions, the IRS can convert the matter into an office audit and ask you to come in. That is rare, but it happens when the paper trail looks thin or inconsistent, which is one more reason to answer cleanly the first time.

If a letter shows up and you are not sure what it wants, our audit and notice assistance team reads it the same hour and tells you what is actually at stake. You can start a conversation at our new client inquiry page and we will take it from there, deadline and all.

One more thing about timing that trips people up. The interest on a proposed balance keeps running from the original due date of the return, not from the day the letter arrives. So a number that looks fixed on the page actually grows a little each month it stays open. That is not a reason to overpay a wrong figure, but it is a reason to answer promptly once you know the figure is right. I tell clients to treat the response deadline as the real deadline and the interest clock as the quiet one running underneath it. Both matter, and both reward a fast clean answer over a slow defensive one.

Mail audits are not random in the way people fear. They run off matching and scoring. The biggest single trigger is a document mismatch. Every employer, bank, brokerage, and platform that pays you also files a copy with the IRS. A computer compares those copies against your return. When a number is missing or off, you get a CP2000. That one notice drives a huge share of all correspondence audits, and it is purely arithmetic. Leave a 1099-K from a payment app off your return and the system catches it without a human ever looking at your file. There is no judgment in it, just a comparison that did not balance.

The second trigger is a scoring model the IRS runs on every return. It rates how far your numbers sit from what is typical for your income and occupation. A bartender reporting 40,000 dollars in wages and 38,000 dollars in unreimbursed business expenses scores high. So does a return claiming a refundable credit the filer may not qualify for. That is where the CP75 notice comes in. It asks an Earned Income Tax Credit claimant to prove the child lived with them and that the income figures hold up. School records, a lease, and a doctor letter usually settle it without much drama.

The notices I see most, roughly in order, are these. CP2000 for underreported income. Letter 566 as the general exam request. CP75 and its cousin CP75A for the EITC. Letter 525 carrying the examiner findings. Each one names a tax year and a response deadline. None of them mean you did something wrong. They mean the IRS wants paper, and the faster you give it the right paper, the faster the whole thing ends.

Here is a worked example. A two-partner consulting LLC in Queens deducted 22,000 dollars in travel and meals against 140,000 dollars of revenue. The ratio tripped the score and a Letter 566 arrived asking for receipts and a business-purpose log. We had calendar entries, hotel folios, and client emails for every trip. We mailed a tabbed packet keyed to each expense, with a short note explaining the business reason for each. The reviewer accepted it and closed the case with no change. The audit cost the client a Saturday of digging through old email and nothing more. No extra tax, no penalty, no follow-up.

The mistake we see every year is sloppy reporting of platform income. Rideshare, resale apps, freelance marketplaces, and crypto exchanges all file information returns now. People treat that money as invisible, and it is the opposite of invisible. If you earn it, report it, and keep the cost records that offset it. Clean individual tax return preparation up front prevents most of these letters from ever printing in the first place, which is the cheapest audit defense there is.

An edge case worth knowing is that amended returns and very large refunds also draw a closer look. An amendment that suddenly claims a big deduction you skipped the first time can trigger a request for proof. That is not a penalty, it is verification, and a clean packet clears it. Keep your backup for at least three years, because that is the window the IRS usually works within. If you want a second set of eyes before a letter ever arrives, reach our team at the new client inquiry page.

It also helps to know how the IRS gets the information that triggers these letters. Payers file their copies in late winter, the matching program runs through the year, and notices often print a full year or more after you filed. That lag is why a CP2000 for a 2023 return might not reach you until late 2025. People assume an old year is closed and safe. It is not, until the matching has run and the assessment window has passed. Keep the records for the year you filed, not just the year you are living in, because the letter about an old return is the one that surprises people the most.

Respond on time, respond completely, and make the reviewer job easy. Those are the three things that close a mail audit fast. The letter gives you a deadline, almost always thirty days from the date printed on it, not the date you opened it. Calendar that date the moment the envelope arrives. If you need more time, you can call the number on the notice and ask for an extension, and the IRS usually grants a short one. Silence is the one thing that genuinely hurts you, because the Service reads no answer as a concession that it was right.

Start by reading which item is in question and which year. A CP2000 names the exact income document it thinks you missed. A CP75 lists the EITC proof it wants. Build your packet around that list and nothing else. Do not volunteer documents for items the IRS did not ask about, because that can widen the look. You answer the question on the table, not a broader one you imagined.

Organize the paper. Put a one-page cover letter on top that says, in plain sentences, what you agree with, what you dispute, and what is attached. Number each document. Reference those numbers in your cover letter so the reviewer can follow along without hunting. For income, attach bank statements and the 1099s. For deductions, attach receipts, canceled checks, mileage logs, and a short note tying each cost to its business purpose. Keep the originals at home. Send copies only, by certified mail or fax, and save your proof of sending in case the response is ever questioned.

Here is the irs correspondence audit explained as a real response. A freelance editor got a CP2000 proposing 4,200 dollars over a 1099 she had actually reported, but under a slightly different business name. The IRS matching system did not connect the two. We mailed a cover letter, a copy of her Schedule C showing the income already there, and a one-line explanation of the name difference. The case closed with no additional tax in about nine weeks. The income was never missing. The match simply failed, and a clear letter fixed what a computer could not.

The mistake we see every year is people mailing a shoebox. They photocopy a stack of unlabeled receipts and hope the reviewer sorts it out. The reviewer will not. An unorganized response gets read as a weak response, and weak responses draw follow-up letters or a no-change denial. Spend the extra hour labeling and tabbing. It changes outcomes, and I have watched it change them in both directions over the years.

One edge case is worth a sentence. If you genuinely owe the additional tax, you can sign the response form agreeing to it and set up a payment plan in the same envelope. You do not have to fight a number that is correct, and dragging it out only adds interest. Our notice and audit team builds these packets for clients constantly, and good tax compliance support keeps the records ready before any letter shows up. Start at the new client inquiry page if a deadline is already running.

A short word on how to send the packet matters too. Fax tends to land in the reviewer queue faster than mail, and it gives you a transmission confirmation the same minute. If you mail it, use certified mail with return receipt so you have dated proof the IRS got your response before the deadline. I have seen a perfectly good answer get treated as a non-response because the taxpayer dropped it in a regular envelope and could not prove it ever arrived. The proof of delivery is cheap insurance, and it is the first thing I ask a client to keep when we build a response together. Keep a dated copy of the full packet for yourself too, because if a follow-up letter ever questions what you sent, you want to hand over the exact same pages without rebuilding them from memory weeks later.

Ignoring a correspondence audit is the worst path, because the IRS does not drop the matter when you go quiet. It proceeds without you. After your deadline passes with no response, the Service issues a Letter 525 or a Statutory Notice of Deficiency, often called a 90-day letter. That notice assesses the tax the way the IRS proposed it, plus penalties and interest, as if every flagged item were disallowed. You lose the chance to show the documents that would have helped. The bill becomes real, and collection can follow with liens and levies if it goes unpaid long enough.

Disagreeing is completely different and completely allowed. If you think the IRS is wrong, you say so in writing and attach your proof. If the reviewer still disagrees after reading your packet, you have appeal rights. The IRS Office of Appeals is a separate, independent group whose job is to settle disputes without going to court. You request a conference, usually by phone, and an appeals officer who never touched your case looks at it fresh. Preparing a request for Appeals has specific content rules, and a clear written protest moves the case faster than a vague one ever will.

If Appeals does not resolve it, the 90-day letter gives you ninety days to petition the United States Tax Court. This is the one forum where you can dispute the tax without paying it first. You file a petition, the case is docketed, and most Tax Court matters settle with IRS counsel before any hearing ever happens. You do not need a lawyer to file, though representation helps once the stakes climb into real money. The ninety days is a hard count from the date on the letter, not from the day you read it.

Here is a worked example. A retired teacher in the Bronx got a CP2000 over a pension rollover the IRS read as a taxable distribution. She missed the first deadline while traveling, and a 90-day letter arrived. We filed a Tax Court petition to preserve her rights, then sent IRS counsel the 1099-R coding and the trustee-to-trustee transfer confirmation. Counsel agreed the rollover was nontaxable, and the case settled at zero additional tax before a courtroom date was ever set. The petition bought the time the missed deadline had cost her, and it cost far less than the tax would have.

The mistake we see every year is treating the 90-day letter as junk mail. It is the most important envelope the IRS sends, because the ninety-day clock is hard and unforgiving. Miss it and you generally must pay the tax first and then sue for a refund later, a far harder and slower road. The edge case worth knowing is that if you can show you never received an earlier notice because the IRS used an old address, you may be able to reopen the matter through audit reconsideration even after assessment.

Whether you agree, disagree, or need to push a case to Appeals, our audit and notice assistance service handles the correspondence and the deadlines so nothing slips. If a 90-day letter is in your hand right now, do not wait. Reach us through the new client inquiry page the same day you open it.

People also ask whether hiring representation makes the IRS think they are hiding something. It does not. A power of attorney on file simply means a professional handles the back and forth, and reviewers deal with represented taxpayers all day. If anything, a clean represented response moves faster because it speaks the IRS language and answers the actual question on the first pass. The point of representation is not to fight for the sake of fighting. It is to give the Service what it needs in the form it expects, so the case closes at the right number instead of dragging through extra letters. And if the reviewer still disagrees after a clean answer, a represented taxpayer already has the protest and the appeal path mapped, which keeps the next step from becoming a scramble against the clock.

The three audit types differ in where they happen, who runs them, and how wide they reach. A correspondence audit happens entirely by mail, runs through a service center reviewer rather than a named agent, and looks at one or two items. An office audit asks you to bring records to a local IRS office and sit with a tax compliance officer, who can probe several areas of one return in a single sitting. A field audit sends a revenue agent to your home, your business, or your representative office, and it is the broadest of the three by a wide margin. Knowing which one you face tells you how hard to prepare.

Scope is the clearest divider. IRS audits by mail stay narrow on purpose. The letter names the items, you answer those items, and the case closes. Office audits widen the lens. The officer may start with your travel deductions and then ask about your income sources or your filing status in the same meeting. Field audits go widest of all. A revenue agent can examine multiple years, walk through your accounting system, tour a business location, and interview you directly. The deeper the scope, the higher the dollars usually at stake, and the more a represented strategy matters.

Who you deal with also changes. In a mail audit you correspond with a rotating pool of reviewers, and you may never speak to the same person twice. In an office audit you have one tax compliance officer assigned to your file. In a field audit you have one revenue agent, typically a more senior examiner assigned to more complex returns. That continuity cuts both ways. One examiner can build context in your favor over a few conversations, or dig deeper than a mail reviewer ever would because they have the time and the mandate.

Here is a worked example. A restaurant owner in Harlem first got a mail notice questioning a single equipment deduction. We answered it with the invoice and closed it in weeks. Two years later the same client drew a field audit covering three years of returns. A revenue agent visited the restaurant, reviewed point-of-sale records, and tested cash deposits against reported sales. That examination took four months and a stack of reconciliations. Same taxpayer, two completely different experiences, because the scope was completely different and the second one reached into the whole operation rather than one line.

The mistake we see every year is people preparing for a field-level fight when they only have a mail-level question, or worse, treating a field audit as casually as a letter. Match your effort to the audit. A correspondence audit needs a clean documented packet and a calm reading of the notice. A field audit needs a represented strategy, organized books, and careful control of what the agent sees and which questions you answer. The edge case is that a mail audit can escalate to an office or field audit if your answers raise broader doubts, so even a narrow letter deserves an accurate, consistent response.

Strong tax compliance habits and careful return preparation are what keep most clients in the cheap mail-only lane and out of the field-audit lane entirely. If any of the three lands on you, start at the new client inquiry page and we will scope it correctly before you respond to anything.

There is a cost angle clients always want to understand. A mail audit you can often handle with a few hours of organized work. An office audit usually means a half day and some preparation. A field audit can run months and reach deep into your records, which is why the dollars and the professional time both climb with scope. The lesson is to take the small letter seriously so it stays small. A tidy answer to a narrow notice is the cheapest insurance against the broad and expensive examination, and it is almost always within reach if you act before the deadline rather than after it.