What Are IRS Letters?

Read this first

The code tells you everything

Top-right corner. Find it before you do anything else. Most letters are automated, and very few are audits.

Use the printed date

Do not recalculate from the day it arrived. A notice that sat in a forwarding queue may already have lost part of its window.

30 days = Appeals, 90 days = Tax Court

The 30-day letter offers you Appeals. The 90-day letter is the last stop before the tax is assessed.

Send us the letter

Photograph both sides and send it over. We will tell you which notice it is, what the real deadline is, and whether it needs a reply at all. Call (212) 641-0673 or use the contact form. No charge for identifying the notice.

Send the contact form (212) 641-0673

What an IRS letter is

Written notice about your tax account

An Internal Revenue Service letter, usually just called an IRS letter, is a written notice about your tax account, and almost all of them are generated automatically. The code printed in the top right corner tells you which one you have. Codes beginning with CP come out of a computer system. Codes labeled Letter or LTR come from a particular department and usually name a person or a unit.

Receiving one does not mean you are under audit. The IRS mails millions of these every year, and the large majority are balance reminders, requests for a missing form, or notices that a refund was adjusted. What decides how serious your letter is, and how fast you have to move, is the code and the date.

01How to read it

How to read an IRS letter: five steps

Everything you need is on the first page: the notice code, the tax year, and the response date.

Find the notice code
Top right corner. CP followed by a number, or Letter followed by a number and sometimes a letter (e.g. 4883C). Enter it in the IRS notice-and-letter search to confirm the code is real before you read another word.
Find the tax year
A notice about 2022 is a different problem from a notice about last year's return, and it changes what you need to pull.
Find the response date, if there is one
Several letters ask for nothing. Where a due date is printed, that is the one that governs — do not recalculate it from the day the envelope arrived.
Compare the letter to your own records
Pull the return for that year, and where a third party is involved, your wage and income transcript. The IRS is often working from a document you never received.
Decide whether it needs a reply at all
Replying to notices that ask for nothing puts your file back into a queue and adds weeks.

02Real vs scam

How to tell a real IRS notice from a scam letter

The IRS normally opens contact by U.S. Mail. It calls only in limited cases and emails or texts only with your permission.

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Real notices carry a code

Scam letters usually have none, or invent one that does not exist on the IRS notice list.

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Real notices never demand a payment method

Gift cards, cryptocurrency and prepaid debit cards are always a scam. Wire payments are legitimate, but only when you start one yourself through your own bank.

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Real payments go to the U.S. Treasury

Never to an individual, a law firm, or a company name.

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Real notices tell you what to do next

Where appeal rights apply, the notice sets them out. Threats of immediate arrest, deportation, or license suspension are not how the IRS writes.

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Verify independently

Look up the code on the IRS notice page and call the IRS on its published number — never the number printed in a letter you doubt.

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A social media direct message is never from the IRS

The agency keeps a running list of current tax scams and consumer alerts.

03The two deadlines that matter most

30 day letter vs 90 day letter: Appeals or Tax Court

30 day letter

Letter 525 · Letter 915 · CP2000

Proposes changes — opens Appeals

Three choices. Agree and sign. Disagree in writing and send the documents that support your position. Or ask for Appeals, which is a separate office from the one that proposed the change and is not bound by its conclusions.

Do nothing and none of those choices survives — a 90-day letter follows.

90 day letter

CP3219A · Letter 3219 · Letter 531

Statutory Notice of Deficiency — Tax Court

Under Section 6213(a), 90 days from the mailing date — 150 if addressed outside the US — to petition the Tax Court.

The IRS has no power to extend that deadline, and no amount of talking to a revenue agent stops the clock.

Equitable tolling — Buller, Culp, Oquendo

For decades, missing the 90 days simply ended the matter, and the Tax Court still treats the deadline that way. Three appellate courts now disagree.

The Second Circuit, which is where a New York taxpayer’s appeal goes, held in Buller v. Commissioner in 2025 that the deadline is a claim-processing rule rather than a jurisdictional bar, and that it can therefore be equitably tolled. That followed the Third Circuit in Culp and was joined by the Sixth Circuit in Oquendo.

None of it changes what you should do. Equitable tolling is an argument you make after you have already lost the safe route. Treat the 90 days as hard and file inside them.

Check your deadline. Send us the notice date and the code. We will work out the actual last day to respond.

04Notice codes

Types of IRS letters, by notice code

IRS notice codes fall into five groups. Deadlines shown are the standard ones — the date printed on your own letter always governs.

Balance-due and collection notices

The sequence. Each step narrows what you can still do about it.

Notice	What it means	Deadline	If ignored
CP14	The first bill — return processed, you owe, account opens.	21 days	Penalties and interest keep running; sequence begins.
CP501	First reminder that the balance is still open, ~5 weeks after CP14.	Date on notice	Moves to CP503 and toward levy notices.
CP503	Second reminder. Nothing heard, balance unchanged.	Date on notice	CP504 follows and the tone changes.
CP504	Notice of intent to levy your state tax refund.	30 days	IRS can take state refund; final levy notice next.
CP90	Final Notice of Intent to Levy for individuals — hearing right opens.	30 days (CDP hearing)	Wages, bank accounts and property become leviable.
CP297	Same final levy notice, issued to a business.	30 days	Business accounts and receivables become leviable.
LT11	Final Notice of Intent to Levy (ACS).	30 days	Same as CP90. CDP right lapses.
Letter 1058	Revenue officer version of the final levy notice.	30 days	Levy proceeds. Equivalent hearing does not pause collection.
Letter 3172	Notice of Federal Tax Lien filing + hearing right.	30 days from day 5 after filing	Lien stays; selling or refinancing gets much harder.
CP523	Installment agreement in default; IRS intends to terminate.	30 days	Agreement ends, full balance due, levy resumes.
CP508C	Debt certified as seriously delinquent (~$66,000+, indexed).	None — already made	Passport can be denied, refused on renewal, or revoked.

Identity verification letters

None of these is an audit — including Letter 4883C. Anti-fraud holds that stop your return until you confirm you are the person who filed it.

Notice	What it means	Deadline	If ignored
Letter 4883C	Verify identity by phone before the IRS finishes processing.	30 days to call	Return not processed; no refund released.
Letter 5071C	Verify online or by phone — most common identity letter.	30 days	Return stays held indefinitely.
Letter 5747C	Verify in person at a Taxpayer Assistance Center.	Call immediately	Return stays held; refund frozen.
Letter 5447C	Identity verification for a return with a foreign address.	Follow notice route	Same as 4883C.
CP01	Confirmation — identity-theft documentation accepted, account flagged.	None	Nothing. Loop closed.

Audit, examination and proposed change letters

None is a bill — nothing you have not agreed to is assessed until the deficiency process has run its course.

Notice	What it means	Deadline	If ignored
CP2000	Proposed changes — third-party income mismatch. A proposal, not an audit.	30 days (60 if outside US)	90-day letter follows and then tax is assessed.
CP2501	Softer version of CP2000 — mismatch, explanation wanted first.	30 days	A CP2000 follows.
CP2005	The matching case closed with no change.	None	Nothing.
Letter 2205-A	Individual return selected for examination — agent wants to schedule.	Contact within 14 days	Examiner proceeds on IRS-held records.
Letter 2205-B	National Research Program examination — statistical selection.	Contact within 14 days	NRP examinations look at every line.
Letter 2205-L	Initial contact letter for business return examination.	Contact within 14 days	Same as above.
Letter 566	Correspondence audit — IRS wants documents by mail.	30 days	Items disallowed; moves toward 30-day letter and NoD.
CP75	Refund held while IRS examines a credit (EIC, dependent).	Date on notice	Credit denied; sometimes barred for future years.
Letter 915	Examination report — what auditor proposes to change, and why.	30 days	A 90-day letter follows.
Letter 525	General 30-day letter — attaches report and opens Appeals.	30 days	NoD issues; Appeals gets harder.
CP3219A / L. 3219 / L. 531	Statutory Notice of Deficiency — the 90-day letter.	90 days (150 outside US)	Tax assessed; collection starts.

Refund hold and adjustment notices

Most of these are holds rather than problems. A math error notice is not an audit.

Notice	What it means	Deadline	If ignored
CP05	Refund held while IRS reviews income, withholding, or credits.	None (allow 60 days)	Refund stays held.
CP05A	The follow-up — now IRS wants documents.	Date on notice	Credit or withholding disallowed.
Letter 4464C	Return under review before any refund is released.	None	Nothing — hold notice.
CP12	IRS corrected a math or clerical error — refund changed.	60 days to disagree	Correction stands.
CP11	Same math error correction — but result is balance due.	60 days to disagree, 21 to pay	Balance assessed; collection begins.
CP49	Refund applied to a tax debt from another year.	None	Nothing.
CP53A	IRS could not deposit refund electronically — reviewing before mailing a check.	None (call after 10 weeks)	Follow up after 10 weeks.
CP21B / CP22A	An adjustment you asked for was made. CP21B = refund; CP22A = balance.	21 days if balance	Collection notices follow on a balance.

Interim and informational letters

People worry about these needlessly, with one exception — Letter 12C does need a reply.

Notice	What it means	Deadline	If ignored
Letter 2645C	Interim — IRS received something and needs more time (usually 60 days).	None	Nothing. Wait out the stated period.
Letter 2644C	Second interim — IRS needs another period beyond the first.	None	Nothing, though repeated 2644Cs are worth chasing.
Letter 12C	Missing form, schedule, or signature — this one DOES need a reply.	20 days	Return not processed; no refund.
CP01A	Annual Identity Protection PIN for the coming filing season.	None	Cannot e-file without the PIN.
CP79	Credit was disallowed earlier — Form 8862 may be required next time.	Form due with next return	Credit denied again.
CP2100 / CP2100A	Payee TIN mismatches on info returns — can trigger backup withholding.	Date on notice	Backup-withholding obligations and info-return penalties.

05New York State

New York State tax notices (DTF letters)

A federal letter and a New York letter are separate matters with separate deadlines. Resolving one does not resolve the other.

Form DTF-948 / DTF-948-O, Request for Information. New York wants proof of wages, withholding, residency, a dependent, or a credit before it releases your refund. Respond by the date on the letter.
Form DTF-960-E, Statement of Proposed Audit Change. A review has produced additional tax, penalty, or interest. Page two sets out how to request a review.
Notice of Additional Tax Due after a federal change. When the IRS adjusts your federal return you are required to report the change to New York. If you do not, the state eventually assesses it for you.
STAR and property letters. A different unit again, with its own process, not something your income-tax response will touch.

The federal-change rule catches people out. A CP2000 you settled with the IRS two years ago can produce a New York bill you were never expecting, with interest running the whole time.

06Our workflow

How we handle IRS letters

We work the notice from the code to the closing letter. The first thing we establish is the real last day to respond.

Identify and date the notice

Read the code, confirm the tax year, calculate the real last day to respond.

Pull the transcripts

Account, and wage-and-income, for the year in question — so we work from the IRS record rather than the letter alone.

Respond in writing

A documented reply with schedules and substantiation attached, sent so the response date is provable.

Protect the deadline

Appeals requests, Collection Due Process requests on Form 12153, and Tax Court petitions filed inside the window.

Fix the balance

Installment agreements, penalty abatement where facts support it, and offers in compromise where they actually apply.

Handle the New York side

The DTF letter running alongside the federal one, and the federal-change report the state is waiting for.

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On protecting the deadline and on the follow-through

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George Dimov, CPA

“They patiently walked me through the process and the results. Still waiting on the IRS but I believe Dimov did everything they could to make sure there will be no surprises.”

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