IRS Audit Letter: What to Do First and Why It Matters

Key Takeaways

Respond to an IRS audit letter by the printed deadline, send copies rather than originals, and limit your submission to exactly what’s requested.

Point	Details
Read immediately	Confirm the notice number, tax year, and response deadline before doing anything else.
Preserve, don’t over-share	Gather documents tied to the specific issue only; extra records can widen the audit scope.
Copies only	Send photocopies or scans, never originals, and label every page with your name and TIN.
Know your appeal rights	A 30-day letter lets you request Appeals; a 90-day Notice of Deficiency lets you petition Tax Court.
Get help for complex cases	Tolliver Bookkeeping and Tax offers full audit representation, from reviewing the notice to attending examiner meetings.

What Does an IRS Audit Letter Look Like, and What Types Exist?
What Should You Check First on the Letter?
Your First 7 Days: A Day-by-Day Response Plan
What Documents Does the IRS Usually Request?
How Do You Actually Send Your Response?
What Happens After You Respond, and What Are Your Appeal Rights?
How Do You Know a Notice Is Actually From the IRS?
Why Do Some Returns Get Selected for Audit?
When Should You Bring in a CPA, Enrolled Agent, or Attorney?
How Tolliver Bookkeeping and Tax Handles Audit Representation
Sources
FAQ

What Does an IRS Audit Letter Look Like, and What Types Exist?

Not every audit letter means the same thing, and figuring out which type you’ve received tells you almost everything about how much work is ahead. The IRS runs three main audit formats: correspondence (by mail), office (an in‑person interview at a local IRS office), and field (an examiner visits your home or business). A fourth, less common category is the research audit, used for statistical compliance studies rather than a specific red flag on your return.

Correspondence audits are the most common by far and usually involve a single issue, like a mismatched 1099 or an unverified deduction. Office audits go a step further, typically covering itemized deductions, business expenses, or rental income, and require you to appear with documentation. Field audits are the most involved: an IRS examiner reviews your full books, often for a small business with more complex income streams.

The notice number printed on page one tells you which situation you’re in. Here’s how the most common ones break down:

Letter/Notice Code	Audit Type	Typical Response Window
CP2000	Correspondence (income/document mismatch)	30 days
Letter 566	Correspondence (initial audit inquiry)	30 days
CP75 / CP75A	Correspondence (EITC documentation request)	30 days
Letter 566	Office audit examination report	30 days
Letter 2205-A / 2205-B	Field audit notification	Set by examiner, often longer
30-day letter	Proposed changes after examination	30 days to request Appeals
Notice of Deficiency (90-day letter)	Final proposed deficiency	90 days to petition Tax Court

If your letter references a 1099 or W‑2 mismatch, it’s almost certainly a CP2000, and Tolliver Bookkeeping and Tax’s breakdown of CP2000 notices walks through that specific process in more depth.

What Should You Check First on the Letter?

Before you do anything else, pull four pieces of information off the page. Everything downstream, your deadline, your documentation list, your contact person, depends on getting these right the first time.

Notice or letter number — usually in the top right corner (CP2000, Letter 566, CP75A, and so on).
Tax year under review — confirm it matches the return you actually filed that year.
Items under examination — the specific line, deduction, or credit the IRS is questioning.
Assigned contact — name, phone number, and mailing or fax address for your case.
Response deadline — the exact date, not the date you opened the envelope.

A quick checklist glance often looks like this: “Notice: CP2000,” “Tax year: 2024,” “Items: Schedule C mileage deduction,” “Response by: mm/dd/yyyy,” “Contact: [examiner name], [phone].”

Compare every dollar figure the IRS lists against your own filed return, line by line. Sometimes the discrepancy is a simple transposition or a 1099 that was issued twice. Other times it’s a legitimate gap you’ll need documentation to close. Either way, that comparison tells you how big a problem you’re actually dealing with before you spend a weekend digging through boxes.

Match reported income figures against your Schedule C, W‑2s, and 1099s.
Check whether the IRS’s numbers reflect a duplicate filing from a third party.
Note any items the IRS lists that don’t appear anywhere on your original return.

One detail trips up more taxpayers than anything else: the clock starts on the date printed on the letter, not the day it landed in your mailbox. If mail delivery took a week and you only open it ten days later, that time is already gone. Don’t assume you have the full window from the moment you notice the envelope.

Your First 7 Days: A Day-by-Day Response Plan

The first week after an audit letter arrives sets the tone for everything that follows. Move through it methodically rather than reactively, and you’ll avoid most of the mistakes that turn a routine correspondence audit into a drawn-out mess.

Day 0: Read the letter completely. Confirm it’s addressed to you, for the correct tax year, and record the deadline on your calendar immediately.
Day 1: Scan or photocopy the letter itself and start a dedicated folder, physical or digital, for this audit only.
Day 2: Pull your filed return for that tax year and lay it next to the IRS’s stated figures to identify the actual discrepancy.
Day 3: Begin gathering supporting documents tied to the specific items under review, not your entire financial history.
Day 4: Make copies of every document you plan to send and label each page with your name and taxpayer ID number.
Day 5: Decide whether the issue is straightforward enough to handle yourself or complex enough to call a CPA, enrolled agent, or attorney.
Day 6-7: Draft your response or representation authorization, and confirm your mailing method includes proof of delivery.

If a week isn’t enough time to assemble everything, most correspondence audits qualify for a one-time automatic 30-day extension simply by calling the number on the notice and requesting it before the original deadline passes. Call the examiner directly if your letter lists one; use the general IRS helpline only if no direct contact is provided.

Pro Tip: Keep a running log, date, time, who you spoke with, and what was said, for every call or letter connected to this audit. If the case drags on or gets reassigned to a new examiner, that log is often the only record of what was already resolved.

What Documents Does the IRS Usually Request?

The documents an examiner wants almost always map directly to the specific issue flagged in your letter. A mileage deduction question calls for a mileage log, not three years of bank statements. Organizing your response by issue, rather than dumping everything you own into an envelope, keeps the audit narrow and your workload manageable.

Issue Under Review	Typical Documents Requested	Where to Find Them
Unreported income	W-2s, 1099s, bank deposit records	Employer, payer, or your bank’s online portal
Business expense deductions	Receipts, invoices, canceled checks	Vendor records, accounting software exports
Vehicle/mileage deductions	Mileage log, fuel receipts, vehicle records	Mileage tracking app or handwritten log
Charitable contributions	Donation receipts, acknowledgment letters	Charity records, bank statements
EITC eligibility (CP75/CP75A)	Birth certificates, school records, custody documents	Vital records office, school administration
Business income/expenses (Schedule C)	Bookkeeping ledgers, bank statements, contracts	Bookkeeping software (Xero, QuickBooks)

Send copies, never originals. Write your name and taxpayer identification number on every single page you submit, especially if you’re faxing, because the IRS scanning system assigns pages to your file based on that information alone. Keep proof of delivery for anything you mail, whether that’s a certified mail receipt or a fax confirmation sheet.

Group documents by the specific issue, not chronologically or by document type.
Label every page with your name and taxpayer ID before scanning or copying.
Keep a master digital copy of the entire submission before it leaves your hands.

Pro Tip: If an examiner requests a bookkeeping backup file rather than printed reports, that’s typically a field audit request and a sign the examiner wants to test your ledger’s integrity directly. A partner guide on organizing accounting records for an audit covers how to prepare that kind of export cleanly.

How Do You Actually Send Your Response?

Most correspondence audits accept three delivery methods: postal mail, fax, or a secure portal if the letter specifically references one. Mail with a tracking or certified-mail option so you have proof of delivery. If you fax, confirm every page transmitted and printed your name and TIN in the header or footer. In-person drop-off at a local Taxpayer Assistance Center is an option for some notices, though it’s rarely necessary for a straightforward document request.

Your cover letter doesn’t need to be elaborate. It needs to be accurate and complete:

State the notice number and tax year at the top, exactly as printed on the letter you received.
List every document enclosed, in the same order as the IRS’s request.
Include your name, address, and taxpayer identification number on the cover page itself.
Sign and date the letter, and keep a copy for your own file before it goes in the mail.

A short adaptable template looks something like this: “This letter responds to Notice [number] dated [date] regarding tax year [year]. Enclosed are copies of [document list] supporting the [specific line item] reported on my return. Please contact me at [phone] with any questions.” Nothing fancier is required, and over-explaining rarely helps your case.

Assemble copies only, never originals, in the order requested.
Attach a one-page summary listing every enclosure.
Retain a full digital and physical copy of the entire submission.
Mail or fax using a method that generates proof of delivery.

Most correspondence audits qualify for that one-time automatic 30-day extension mentioned earlier, but a Notice of Deficiency works differently: the IRS typically sends that specific notice by certified mail, and the 90-day countdown to petition Tax Court is far less flexible.

Pro Tip: If you’re unsure whether your case is heading toward a proposed deficiency, don’t wait to find out. Tolliver Bookkeeping and Tax’s IRS representation services can review the notice and flag that risk before the response window closes.

What Happens After You Respond, and What Are Your Appeal Rights?

Once your documents land with the examiner, one of three outcomes follows. The best case is “no change,” meaning the IRS accepted your explanation and the return stands as filed. The second is a proposed change, delivered as a 30-day letter, where the IRS disagrees with part of your return and gives you 30 days to either sign the agreement or request an Appeals conference. The third and most serious is a Notice of Deficiency, often called a 90-day letter, which finalizes a proposed tax deficiency and starts a 90-day window (150 days if you’re outside the U.S.) to petition U.S. Tax Court before the IRS can assess the tax.

Timelines vary considerably by audit type. Correspondence audits often resolve within a relatively short time after you submit documentation. Office audits, involving an in‑person interview, tend to take a longer time. Field audits, especially for small businesses with multiple income streams, can extend significantly depending on the complexity of the books involved.

If you disagree with a proposed change, you have real options rather than a forced choice between accepting the number or ignoring the letter. You can request an informal conference with the examiner’s manager, file a formal protest to IRS Appeals, or petition Tax Court once a Notice of Deficiency arrives. Filing Form 2848 (Power of Attorney) lets a CPA, enrolled agent, or attorney speak directly to the IRS on your behalf during any of these stages, which matters if you’d rather not personally negotiate with an examiner. Doing nothing carries its own consequence: an unanswered Notice of Deficiency eventually leads to an assessed tax bill and potential collection action, including liens or levies.

How Do You Know a Notice Is Actually From the IRS?

Scam letters mimicking IRS audit notices have become common enough that verification is now a standard step, not an overcautious one. Real notices share a consistent structure: they arrive by mail, list a specific notice or letter number, reference your Social Security number or EIN, name the tax year under review, and give you a legitimate IRS contact number and mailing address.

Watch for these red flags that separate a scam from a genuine notice:

Any demand for immediate payment by gift card, cryptocurrency, or wire transfer.
Threats of arrest, deportation, or license revocation for not paying on the spot.
A phone call or email claiming to be the IRS opening an audit, since real audits start by mail only.
A callback number that doesn’t match the official number listed on irs.gov.
Pressure to act within hours rather than the weeks a real notice allows.

Legitimate notices also let you check status independently. If your letter lists a contact number, you can often confirm the same case details inside your IRS online account under Records and Status, which is a reliable way to cross-check a suspicious piece of mail before you respond to it.

Pro Tip: Search the exact notice number on irs.gov, or call the general IRS number listed there, never a number printed only on the suspicious letter itself. If the details don’t match, you may be dealing with tax identity fraud, and a partner resource on what tax identity fraud looks like and what to do next covers the reporting steps. If you suspect identity theft or a forged notice, report it to the IRS and contact the Taxpayer Advocate Service directly rather than the number on the letter.

Why Do Some Returns Get Selected for Audit?

Most audits trace back to a handful of recognizable triggers rather than bad luck or a targeted investigation. Income and 1099 mismatches top the list, since the IRS’s automated matching system flags any gap between what a payer reported and what you filed almost instantly. Unusually large deductions relative to your income, Earned Income Tax Credit claims, high total income, unreported foreign accounts, and suspiciously round expense figures (think “$5,000” in office supplies with no supporting detail) all raise the statistical odds of a closer look. A smaller share of audits are purely random, part of the IRS’s ongoing statistical compliance research.

It’s worth remembering that many of these audits are narrow by design. A CP2000 questioning one missing 1099 is not the same animal as a full-scope field audit of your entire business, even though both technically qualify as an “audit.” The Taxpayer Advocate Service is direct about this: receiving a notice doesn’t mean you did anything wrong, and plenty of cases close with no change at all once the documentation lines up.

The best defense against future selection is unglamorous but effective: accurate reporting, consistent recordkeeping throughout the year rather than reconstructed after the fact, and using the correct forms for your income type from the start. Businesses working from clean, contemporaneous books, whether kept in Xero or another platform, tend to resolve audits faster simply because the documentation already exists in an organized form.

When Should You Bring in a CPA, Enrolled Agent, or Attorney?

Not every audit letter requires professional help. A simple CP2000 about a single missing 1099 is often something you can resolve yourself with fifteen minutes of paperwork. But several signals suggest it’s time to bring in representation rather than handle it solo.

Your business return is complex, with multiple income streams, payroll, or inventory involved.
The IRS is requesting extensive books and records rather than a single document.
You received a field audit notice (Letter 2205-A or 2205-B), meaning an examiner wants to visit in person.
The proposed deficiency is large enough to meaningfully affect your finances.
You simply want someone else speaking to the IRS on your behalf.

A professional representative handles several distinct tasks: filing Form 2848 so they’re authorized to speak for you, preparing a complete response packet, negotiating directly with the examiner, attending office or field interviews in your place, and handling the Appeals process if it comes to that. Form 8821 is a lighter version of this authorization; it lets someone receive your tax information but doesn’t let them argue your case or negotiate on your behalf the way Form 2848 does.

Service scope: A typical Tolliver Bookkeeping and Tax audit engagement includes reviewing the notice line by line, preparing and organizing the response packet, submitting documentation with proof of delivery, and representing you directly at examiner meetings so you’re not fielding IRS questions alone.

If your income falls below certain thresholds, a Low Income Taxpayer Clinic may provide representation at little or no cost, a resource worth exploring before assuming professional help is out of reach financially.

Pro Tip: If you’re already unsure whether your case needs a CPA or you can handle it alone, that uncertainty is usually itself the answer. Schedule a case review before the response deadline, not after you’ve already sent something incomplete.

A note from the Tolliver team

We’ve sat across the table from small business owners in Kern County holding an audit letter for the first time, and the fear is almost always bigger than the actual case. Correspondence audits, which make up the bulk of what we see, are usually resolvable with the right documents organized the right way. Office and field audits take more coordination, but they’re not unmanageable when someone who does this regularly is handling the response instead of you guessing at what the examiner actually wants.

If you’d rather have someone else read the letter, build the response, and speak to the IRS on your behalf, our IRS representation page is the place to start, and documents can move back and forth securely through our Client Hub portal without anything getting lost in email.

How Tolliver Bookkeeping and Tax Handles Audit Representation

Tolliver Bookkeeping and Tax is the local alternative to piecing together an audit response on your own or hiring a large firm that’s never seen your books before. Because we handle bookkeeping and tax preparation under one roof for small and medium-sized businesses across Kern County, we’re often already familiar with the return in question, which means less time spent reconstructing records and more time building the actual response.

Our audit engagements cover reviewing the notice, preparing your documentation packet, submitting it with proof of delivery, and representing you directly with the examiner or at an Appeals conference if it gets that far. For businesses whose books need cleanup before a response can even be assembled, our bookkeeping services close that gap first. If you’re a laundromat owner or pet business owner, our LaundryList and Bark Ave specialties mean we already speak the language of your industry’s typical deductions and recordkeeping quirks.

If you’ve received a letter and want a straight answer on what it means for you, request a case review through our IRS Representation page and we’ll walk through your notice, your deadline, and what documentation you’ll need before you send anything.

Sources

Save or print these before your response deadline arrives, since you may need to reference them more than once during the audit.

This article is general information, not a substitute for advice from a qualified financial advisor. Consult a qualified financial professional about your own circumstances before acting on anything here.

FAQ

Will the IRS send you a letter if you are being audited?

Yes. The IRS always initiates an audit by mailed notice and will never start one with a phone call, text, or email.

What triggers an IRS audit letter?

Common triggers include income or 1099 mismatches, unusually large deductions relative to income, EITC claims, high total income, and random statistical selection.

What does an IRS audit letter look like in the mail?

It’s a formal letter with a notice or letter number in the top corner, your tax year and taxpayer ID referenced, a list of items under review, and a specific response deadline.

What office do IRS audit letters come from?

Audit letters come from the IRS campus or local office assigned to your case, with the specific mailing address and contact phone number printed directly on the notice itself.

Should I hire someone to respond to my IRS audit letter?

Simple, single-issue notices like a CP2000 are often manageable on your own, but complex business returns, field audits, or large proposed deficiencies are strong reasons to get professional representation.