IRS Notice · CP2566 / Letter 2566 · 30-Day Letter

CP2566, also called Letter 2566: the IRS has calculated your year

A CP2566 is the IRS's own calculation of a year you didn't file, and it gives you 30 days. Filing your own return is still on the table — for now.

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A CP2566 — the letter practitioners call Letter 2566 — is the IRS's own computation of tax for a year you did not file, with 30 days to respond. It is the last letter in this sequence at which filing a return is simply filing a return.

This is the first letter in the sequence with a number on it, and the number is not yours. Three earlier letters asked for a return. This one says: we calculated it. From the notice: “We didn't receive your tax return, so we calculated your tax, penalty and interest based on wages and other income information reported to us by employers, financial institutions, and others.”

It is a proposal, not an assessment. Nothing has been finally determined and nothing has been billed. You can still file the return, and the IRS says so on the letter.

What has changed is that there is now a date. Thirty days from the date of the letter. The three notices before this one printed no deadline at all; this one does, and missing it produces a Notice of Deficiency — after which filing a return, on its own, gives up a right you currently have.

(800) 236-3741 — the line is answered 24 hours a day, seven days a week. The first call is free, with no obligation and no conditions.

Key takeaways

•A CP2566 is the IRS's proposed calculation of tax for an unfiled year, built from income reported about you by third parties.
•You have 30 days from the date of the letter. The IRS's internal manual calls this document the "30-Day Letter" and states that it "gives the taxpayer 30 days to respond." The specimen prints an absolute date rather than the words "30 days" — the date on your copy governs.
•The IRS's number is computed at a filing status of single or married filing separately, without exemptions, deductions or credits you did not claim. It says so on the letter.
•Filing your own return is still the straightforward option at this stage. That stops being true at the next letter.
•An IRS-prepared return does not start your clocks. Under IRC 6501(b)(3), a return the IRS executes does not begin the limitation period on assessment and collection.
•⚠️ This document has two names. The IRS publishes it as CP2566; the internal manual and most practitioners call it Letter 2566. There is no page or specimen on irs.gov under the name "Letter 2566."

What a CP2566 is

A CP2566 is a proposed tax calculation for a year the IRS has no return for. In its own words: “We didn't receive your tax return, so we calculated your tax, penalty and interest based on wages and other income information reported to us by employers, financial institutions, and others.”

It is the point where the sequence stops asking and starts proposing. The specimen is direct about what happens next:

“You must file your return by [date], or we will assess taxes for you using a filing status of 'single' or 'married filing separate'. This means you may not receive certain exemptions, deductions, or credits that you would otherwise receive if you filed your own return.”

“To avoid the assessment of the proposed amount due, and additional penalty and interest charges, you must file your [year] tax return by [date]. You also have the option to accept our proposed amount due and pay immediately. Keep in mind that this amount may be higher than what you would owe if you filed your own return.”

That last sentence is the IRS telling you its own number is probably too high, and saying why. It is not being generous — it is being accurate about the limits of a computation built from third-party data.

On the name, because it will confuse your research. The IRS publishes this as CP2566, and its specimen header reads “Notice 2566.” The Internal Revenue Manual titles the relevant section “Letter 2566 (30-Day Letter),” and practitioners use that name. There is no “Letter 2566” page or specimen on irs.gov. If you are holding a letter marked CP2566 and finding articles about Letter 2566, they are about the same document.

Your clock

Thirty days from the date of the letter. The Internal Revenue Manual states it in terms: “The letter gives the taxpayer 30 days to respond.”

But your notice prints an absolute date rather than a day count, and the printed date is the one to work to. On the specimen we read, the notice date and the printed response date are exactly thirty days apart. Do not count for yourself — read the date off your own letter.

What the thirty days is for. It is the window in which you can file the return and have it be the return for that year, without any of the complications that arrive later. You can also, if the IRS's figure happens to be right, accept it and pay.

What happens when it passes. The IRS proceeds toward a statutory Notice of Deficiency — a CP3219N — which carries 90 days to petition the United States Tax Court. That is a real right and it genuinely expires, and it introduces a trap that does not exist today: after a Notice of Deficiency, filing a return without also petitioning the Tax Court gives up the ability to contest the liability there.

So the honest description of the thirty days is not “act or something terrible happens.” It is: for the next thirty days your options are simple, and after that they are not.

Sources: IRS Notice CP2566 specimen, irs.gov, read 6 September 2026. IRM 5.18.1.6.5, read 6 September 2026. IRS, “Understanding your CP2566 notice,” reviewed 6 September 2026.

Why their number is higher than yours

Because the IRS is computing from what other people reported about you, and nothing else.

That means every W-2, every 1099, every broker statement — all the income. And it means none of the things that reduce it: no itemized deductions, no business expenses against self-employment income, no credits you did not claim, no dependents the IRS does not know about. Filing status is set to single or married filing separately, which for a married person is often the largest single difference.

We are not going to tell you by how much, and there are two reasons. It depends entirely on your year — for someone with a W-2 and a standard deduction it may be close to right, and for someone with a small business it may be very far off. And a figure here would be a sales claim wearing arithmetic, which is the thing this category does badly.

What we will say is the direction and the reason. The IRS is not overstating your tax to punish you. It is computing with less information than you have, and filing your own return is the only mechanism by which the rest of it reaches them.

The most common single omission on a self-employment year is business expenses. A 1099 reports gross receipts. It reports nothing about what it cost to earn them. On a return built only from 1099s, gross receipts and profit are the same number — which is not a small difference.

What happens if you do nothing

A Notice of Deficiency, then an assessment, then collection.

The Notice of Deficiency is a CP3219N and it is a statutory instrument under IRC 6212. It gives 90 days — 150 if it is addressed to someone outside the United States — to file a petition with the United States Tax Court. That clock runs from the date the notice is mailed, not from when you receive it, and a notice mailed to your last known address is effective whether or not it reaches you. For someone who has moved, which describes a lot of long-term non-filers, that is not a hypothetical.

And there is a structural point that makes waiting worse than it looks. A return the IRS prepares under IRC 6020(b) is described by the Code as “prima facie good and sufficient for all legal purposes” — which sounds final. The next section takes it back for the purpose that matters. IRC 6501(b)(3):

“Notwithstanding the provisions of paragraph (2) of section 6020(b), the execution of a return by the Secretary pursuant to the authority conferred by such section shall not start the running of the period of limitations on assessment and collection.”

So an IRS-prepared return leaves you with the tax assessed and collectible, and none of your own limitation periods started. Filing your own return is what starts them — which means the action this letter is asking for and the action that protects you are the same act.

Penalties continue. Failure to file at 5% of the unpaid tax per month or part of a month, capped at 25%; failure to pay at 0.5% per month, also capped at 25%. Where both apply in a month the filing penalty is reduced by the payment penalty, so the combined figure is 5% a month rather than 5.5%.

What to do in the next 30 days

Step one, and it is the only thing that has to happen this week: get the wage and income transcript for the year, and compare it with the notice. The IRS's figure is built from that transcript. Reading them side by side tells you whether the computation is roughly right or badly wrong, and that determines everything else.

1. Compare the notice against the transcript. Is the income right? Is anything on the notice that is not yours?

2. Work out what is missing from their version. Deductions, credits, a filing status, business expenses, dependents. That gap is the value of filing your own return.

3. File the return inside the thirty days if you possibly can. This is the last stage at which that is simply filing.

4. If you cannot make thirty days, file as soon as you can anyway — the IRS will still accept it — but understand that after the Notice of Deficiency arrives, the filing decision and the Tax Court decision have to be made together.

5. If the IRS's figure is actually right and you can pay it, accepting it is a legitimate answer. The notice offers that and it is not a trap.

6. Do not ignore it because you cannot pay what the return will show. A balance has options. The alternative to filing is a larger balance with fewer.

What is harder than it looks is not the return — it is deciding whether the thirty days is realistic and what to do when it is not. Reconstructing a self-employment year with no records, or a year with a property sale, takes longer than thirty days sometimes. The choice then is between filing something incomplete inside the window and filing something correct outside it, and that is a real decision with consequences on both sides. It is the point at which this stops being administration.

Two things worth reading next, depending on where this goes. Unfiled back tax returns covers what preparing the year involves inside a window like this one. And what happens when the IRS files a substitute for return covers the process this letter is the last step before.

The Non-Filer's First 30 Days

Written for exactly this window. What to get first, how to reconstruct a year from third-party records, and how to tell quickly whether the IRS's figure is roughly right or badly wrong — which is the question that decides whether you are filing in a hurry or filing properly.

A first name and an email address, and it is a mailing list. The figures move and this is how corrections reach you.

[ Get the sheet → ]

Or, given the thirty days: call (800) 236-3741 and read us the proposed amount and what kind of year it was. Whether that number is plausible is usually answerable in a few minutes, and it decides how much of a hurry you are actually in. No charge and no obligation.

Katherine M. Johnson, CPA, CTRS

Katherine M. Johnson is a licensed CPA with over 30 years of experience and a Certified Tax Resolution Specialist (CTRS). She personally handles every case — representing individuals and businesses before the IRS and state revenue departments nationwide.

Read full bio

The Kentucky note

A federal computation for an unfiled year does not produce a Kentucky one, and Kentucky may already be running its own. The two are separate processes on separate timetables, and a Kentucky assessment can arrive independently.

And if one has arrived, it carries the harder of your two deadlines — missing the federal thirty days costs you simplicity, while missing the state's window costs the right to argue at all. Kentucky's Notice of Tax Due carries a 60-day protest window under KRS 131.110 — running from the date of the notice rather than from receipt, and the protest must be in writing. The Department of Revenue then says a 25% cost-of-collection fee may be added to unpaid tax 60 days after the original notice date, at a rate set by KRS 131.440(1)(a)1, that trigger being the department's administrative practice rather than statutory text.

So the thirty days on your federal notice is not the only clock that might be running. If you have a Kentucky liability on the same year, its protest window is the shorter path to a permanent loss of rights. Kentucky's Notice of Tax Due sets both out →

What we see

By this letter the number on the page has usually become the whole problem in the reader's mind, and it is the least reliable thing in the envelope.

And something worth saying to the person rather than about the notice: receiving a computed year does not mean the IRS has concluded anything about you. It is an automated process that ran because a return was not there. It carries no finding, no judgment and no note about the reason — and the thirty days is a genuine opportunity rather than a punishment, because it is the last point at which the ordinary answer works.

The first thing we do is put the wage and income transcript next to the notice, because that comparison — not the size of the figure — is what tells you whether this is an arithmetic gap or a genuine dispute, and it does not take long. The question people are most reluctant to raise is what happens if thirty days is not realistic, and it is far better asked early than late; the answer turns on what the year actually contains, and it is a strategy conversation rather than a race. And it is worth saying about this desk rather than about the IRS: nobody here asks why the year went unfiled, because it has never once changed a step of the work. Reading a proposed figure against a transcript is a small first step, and it is one that is available to you today.

Katherine — You're welcome to replace this with what you actually see at the thirty-day letter.

If you would rather ask than read: (800) 236-3741. You do not have to have decided anything, and you do not have to have opened the rest of the envelopes.

Where this sits in the sequence

Notice	What it adds
CP59 → CP515 → CP516 → CP518	Three requests for a missing return, none with a deadline.
▶CP2566 (Letter 2566)You are here	The IRS's own computation. 30 days. The last stage at which filing is simply filing.
CP3219N	Notice of Deficiency. 90 days to petition the Tax Court, and a trap for anyone who files without petitioning.
CP14	Where an assessed balance goes next: the first bill, and the collection sequence.

See the full library: All IRS notices →

Common questions

Is this a bill?

No. It is a proposal. Nothing has been assessed and you are not being asked to pay a determined amount — you are being told what will be assessed if you do not file.

Can I still file my own return?

Yes, and at this stage that is the ordinary answer. The IRS says on the notice that filing your return is how to avoid the proposed assessment. This is the last letter at which filing carries no complications.

What if their number is right?

Then accepting it and paying is a legitimate response, and the notice offers it. That is more common for a straightforward W-2 year than for anything involving self-employment.

Is Letter 2566 the same thing?

Yes. The IRS publishes it as CP2566; its internal manual and most practitioners call it Letter 2566. There is no separate document.

What if I can't get the return done in thirty days?

File as soon as you can. The IRS will still accept it and the deadline does not close the door on filing. What it does close is the simplicity — after the Notice of Deficiency arrives, filing without also petitioning the Tax Court gives up the right to contest the liability there, so the two decisions have to be made together.

Will they add penalties on top of their calculation?

The notice states that its figure already includes penalty and interest, and both continue to accrue while the balance stands.

This page explains how IRS notices and the rules behind them generally work. It is not tax or legal advice about your situation, and reading it does not create a client relationship. Figures are current as of the last-reviewed date above.

The question that decides whether you need anyone, and it is not the amount

Is the IRS's number roughly right?

If the year was a W-2 year and you would have taken the standard deduction, their figure may be close — and in that case this is a simple late return, or even a decision to accept and pay. There is free filing help staffed by IRS-certified volunteers: VITA for people who generally make $69,000 or less, for people with disabilities and for limited-English-speaking taxpayers, and TCE for people aged 60 and older. ⚠️ With a deadline running, check first whether the site prepares prior-year returns — they are built around the current season and it varies by location.

The number is badly wrong, and the gap is worth real money, in these situations:

Self-employment income on the transcript. A 1099 reports gross receipts and says nothing about expenses. On the IRS's version, receipts and profit are the same figure.
You are married. The computation uses single or married filing separately, and that alone can move the number substantially.
A property sale, a retirement distribution or canceled debt appears on the transcript as a gross figure, with no basis and no exclusions.
Dependents, education credits, or anything the IRS has no record of.
Income on the notice that is not yours — a mismatched 1099, an old employer, identity theft.

And two situations where the issue is not the number at all:

You cannot realistically file inside thirty days. That is a strategy question rather than a filing question, and it is the one thing on this page that is genuinely time-sensitive.
Several years are in the same position and this notice covers one of them.

If you cannot tell whether the number is plausible, that is a short call rather than an engagement. Reading a proposed figure against a transcript to see whether it is in the right postcode takes minutes.

On what is actually stopping you, which is probably not the number on the letter.

For most people at this stage the hard part is that they have not told anyone. The call is confidential. Nothing is reported because you made it, and no CPA can contact the IRS about you or file anything for you without a signed authorization. You can find out whether the IRS's figure is plausible and then decide what to do with that.

A real office, twenty minutes from Lexington: 240 Blossom Park Drive, Suite 3, Georgetown, Kentucky.

Here: Katherine works the account herself and you are not handed to a case manager. The first thing that happens is the transcript against the notice, because whether their figure is plausible determines everything else. And if their number is about right and the year is simple, that is what you are told on the first call.

The first call is free, it is thirty minutes, and there is no obligation at the end of it. Two things start it: the proposed amount, and what kind of year it was.

(800) 236-3741 — answered 24 hours a day, seven days a week. After hours you reach an AI receptionist rather than voicemail: it answers common questions, takes your details, and books the first available thirty minutes. Or Book a time →.

Call (800) 236-3741 Book a time

The NLTR Office ·

Reviewed by Katherine M. Johnson, CPA, CTRS