Tax Notice of Assessment: Deadlines, Appeals, and Payment Options

A tax notice of assessment is the letter the IRS sends after processing your return, showing its calculation of what you owe or what refund you’re due for a specific tax year. It may confirm exactly what you filed or propose changes based on information the IRS received from employers, banks, and other third parties. What you should do next depends entirely on which notice you’re holding and whether its numbers match your records. Some of these letters carry hard deadlines that, if missed, cost you the right to challenge the IRS in Tax Court without first paying the disputed amount. Interest on unpaid tax currently runs at 7% per year, compounded daily, so the cost of waiting is real.¹

What the Notice Actually Says

The notice lays out the IRS’s math for the tax year: total income reported, deductions and credits accepted or changed, and the final balance showing either a refund or an amount owed. If the IRS adjusted anything, the notice explains what changed and why. Most adjustments come from mismatches between what you reported and what third parties reported to the IRS under your Social Security number.

If you owe, the notice also shows any penalties and interest already added. The IRS compounds interest daily on unpaid balances, and the rate resets quarterly based on the federal short-term rate plus three percentage points. The individual underpayment rate is 7% per year for the first quarter of 2026 and has moved between 3% and 8% in recent years.²

Which Notice Are You Holding

Not every IRS letter works the same way, and treating one as another is how deadlines get missed. The code in the upper corner of the notice tells you which type it is.

CP14 (Balance Due). The most common notice. It says you owe money on the return as you filed it and states the amount due, including penalties and interest. Pay by the date on the notice, or contact the IRS about payment options before that date.³
CP2000 (Underreported Income). The income or deductions on your return don’t match what third parties reported. This is a proposal, not a bill and not an audit. You typically have 30 days to respond, 60 if you’re outside the United States.⁴
Letter 3219 / CP3219N (Notice of Deficiency). The “90-day letter.” It formally proposes a deficiency and gives you 90 days (150 if you’re outside the U.S.) to petition the U.S. Tax Court before the IRS can legally assess the additional tax. Miss it and you lose the right to challenge the assessment in Tax Court.⁵

Most assessment disputes start with a CP2000. The IRS processes billions of information documents each year, and its automated matching system flags anything that doesn’t line up. Sometimes the mismatch is real, like unreported freelance income. Other times it’s a timing issue, a misclassified document, or income you properly excluded that the IRS didn’t recognize. Either way, respond by the deadline with documentation.⁶

One boundary worth flagging: if you never filed a return for the year in question, the IRS can prepare one for you using the third-party data it has, called a substitute for return. Those substitute returns almost always inflate the bill because the IRS won’t give you deductions or credits you didn’t claim, and the failure-to-file penalty stacks on top at 5% per month up to 25%.⁷⁸ Filing your own late return is almost always cheaper than letting that stand.

Review the Notice Line by Line Before You Do Anything

Before you pay and before you dispute, check the notice against your own records. This is where errors surface, both yours and the IRS’s.

Start with the income figures. Compare every income item on the notice to your W-2s, 1099s, and K-1s. If the IRS shows income you don’t recognize, pull your IRS account transcript online to see which information documents were filed under your Social Security number. Mismatches often trace to a former employer reporting under the wrong taxpayer identification number, or a brokerage reporting the full proceeds of a stock sale without accounting for your cost basis.

Next, check the deductions and credits. If the IRS disallowed something, the notice should explain why. Common reasons include missing documentation, income-based limits, or eligibility issues with a credit. Gather receipts, bank statements, donation acknowledgment letters, tuition statements, and anything else that supports what you originally claimed.

Verify the penalties and interest too. If you filed on time and paid late, the failure-to-file penalty shouldn’t appear. If you paid in full by the return due date but the notice shows interest, something is off. Mechanical errors are less common than income mismatches, but they happen.

The Penalties You’re Likely Looking At

When the balance on a notice is larger than you expected, penalties are usually why.

Failure to file. 5% of unpaid tax per month or partial month the return is late, capped at 25%.⁸
Failure to pay. 0.5% of unpaid tax per month, capped at 25%. Drops to 0.25% per month once you’re on an approved payment plan.⁹
Accuracy-related penalty. 20% of the underpayment when the IRS finds negligence, disregard of the rules, or a substantial understatement of income.¹⁰

When a return is both late and unpaid, both penalties run at the same time, but the combined charge in any single month can’t exceed 5%. The failure-to-file penalty absorbs the failure-to-pay penalty during those months. Once the filing penalty hits its 25% cap after five months, the payment penalty keeps running on its own.¹¹

If You Agree With the Notice

If the numbers are right and you owe, pay as fast as you can. Interest compounds daily, so every day of delay adds to the total.

IRS Direct Pay lets you pay from a bank account for free without registering an account. You can also pay by debit or credit card (processing fees apply) or mail a check to the address on the notice. If you’ve never filed a return or haven’t filed in more than six years, Direct Pay won’t work and you’ll need another method.¹²

If the notice proposed changes (like a CP2000) and you agree, sign and return the response form by the deadline. The IRS will then assess the tax and send a follow-up bill. Agreeing informally by phone without returning the form can leave the case open and trigger unnecessary follow-up notices.

If You Disagree

Disagreeing takes documentation, not a phone call. The exact route depends on the notice and the amount.

For a CP2000 or similar proposed adjustment, respond in writing by the deadline. Include a clear explanation of why you disagree and attach copies (not originals) of every document that backs your position.⁴ If the IRS proposed adding unreported income, show that it was already on the return elsewhere or that it wasn’t taxable. If a deduction was disallowed, send the receipts or records that prove eligibility.

For proposed changes coming out of an audit, the process branches on dollar amount. If the total proposed increase in tax and penalties is $25,000 or less per tax period, file a Small Case Request using Form 12203.¹³ Above $25,000, the IRS requires a formal written protest with your contact information, the specific items you’re disputing, the facts supporting your position, any legal authority you rely on, and a signed declaration under penalties of perjury.¹⁴

Mail the dispute to the address on the letter that offered you appeal rights, not directly to the IRS Independent Office of Appeals. Sending it to the wrong address can delay your case or keep Appeals from considering it.¹⁵

Appeals and the 90-Day Tax Court Deadline

The IRS Independent Office of Appeals is a separate function within the IRS that reviews disputes impartially. You generally have 30 days from the date of the letter offering appeal rights to submit a request.¹⁵ Appeals officers can settle cases based on the hazards of litigation, meaning they weigh how likely the IRS is to win in court and negotiate accordingly. Many disputes end there.

If Appeals doesn’t resolve it, the office will issue a Notice of Deficiency, and that letter is your ticket to Tax Court. Once the IRS mails it by certified or registered mail, you have exactly 90 days to file a petition, or 150 days if the notice is addressed to you outside the United States.¹⁶ During that window, the IRS cannot assess the deficiency or take collection action. The real advantage of Tax Court is that you can contest the IRS’s determination without paying first.

Miss the 90 days and the Tax Court cannot hear your case. The IRS will assess the tax, and your only option is to pay the full amount, file a claim for refund, and then sue for a refund in federal district court or the U.S. Court of Federal Claims. That path is far slower and more expensive.⁵ The 90-day deadline is the single most important date in any tax dispute.

If You Can’t Pay the Full Balance

Owing more than you can pay right now doesn’t leave you without options. Applying for one of these before collection starts gives you more leverage.

Short-Term Payment Plan

If you can pay in full within 180 days, you can set up a short-term plan with no setup fee. Individuals owing less than $100,000 in combined tax, penalties, and interest can apply online. Penalties and interest keep accruing until the balance is paid.¹⁷

Long-Term Installment Agreement

For balances you need longer to pay, a monthly installment agreement stretches payments out. You can apply online if you owe $50,000 or less and have filed all required returns. Setup fees as of March 2026 range from $22 (online, direct debit) to $178 (phone or mail, non-direct debit), with reduced fees for low-income taxpayers.¹⁷ Once approved, the failure-to-pay penalty drops from 0.5% to 0.25% per month.⁹

Offer in Compromise

An Offer in Compromise lets you settle for less than the full amount if you genuinely can’t pay it all. The IRS weighs your income, expenses, asset equity, and ability to pay, and generally accepts an offer when it reflects the most the agency can realistically collect. You must have filed all required returns, made all required estimated payments, and not be in an open bankruptcy proceeding. The IRS has a Pre-Qualifier Tool on its website to check eligibility before you apply.¹⁸

Currently Not Collectible Status

If paying anything at all would keep you from covering basic living expenses, you can ask the IRS to place your account in currently not collectible status. You’ll complete a financial disclosure form and provide proof of your situation. Active collection is suspended while you’re in this status, but penalties and interest keep accruing and the IRS may file a federal tax lien to protect its interest in your assets.¹⁹ The IRS re-evaluates your ability to pay periodically.

Getting Penalties Removed

Penalties on an assessment aren’t always final. The IRS has two main paths to remove or reduce them.

First-Time Penalty Abatement

If you’ve been compliant for the past three years, meaning you filed all required returns and had no penalties during that period (or any penalties were removed for an acceptable reason), you can request first-time abatement for failure-to-file, failure-to-pay, or failure-to-deposit penalties.²⁰ This is the easiest penalty relief to get. Call the number on your notice, and the representative can apply it immediately if you qualify. No formal paperwork needed.

Reasonable Cause

If first-time abatement doesn’t apply, you can request relief by showing reasonable cause, meaning you exercised ordinary care but still couldn’t comply. Circumstances the IRS considers valid include fires or natural disasters, serious illness, death of an immediate family member, and inability to obtain necessary records. Not knowing the rules, running short on money, or blaming your tax preparer generally won’t qualify on their own. The IRS decides these case by case, and the strength of your documentation matters.²¹

What Happens If You Ignore It

Silence is the worst response, and it’s more common than you’d think. Ignore a CP2000, and the IRS treats the proposed changes as accepted and assesses the tax. Ignore a CP14 balance, and the failure-to-pay penalty keeps growing until the IRS moves to enforced collection: wage garnishment, bank levies, federal tax liens. Ignore a Notice of Deficiency for 90 days, and the IRS assesses the full proposed amount plus penalties and interest, and you permanently lose the right to challenge it in Tax Court without paying first.¹⁶

Even if you can’t pay, and even if you’re not sure whether the IRS is right, respond by the deadline. A timely response preserves your rights.

1
Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026
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Internal Revenue Service. Quarterly Interest Rates
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Internal Revenue Service. Understanding Your CP14 Notice
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Internal Revenue Service. Topic No. 652, Notice of Underreported Income – CP2000
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Taxpayer Advocate Service. Letter 3219, Notice of Deficiency
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Internal Revenue Service. Understanding Your CP2000 Series Notice
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Office of the Law Revision Counsel. 26 USC 6020 – Returns Prepared for or Executed by Secretary
8
Internal Revenue Service. Failure to File Penalty
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Internal Revenue Service. Failure to Pay Penalty
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Internal Revenue Service. Accuracy-Related Penalty
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Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax
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Internal Revenue Service. Direct Pay With Bank Account
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Internal Revenue Service. Request for Appeals Review (Form 12203)
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Internal Revenue Service. 4.24.10 Appeals Referral Procedures
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Internal Revenue Service. Preparing a Request for Appeals
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Office of the Law Revision Counsel. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court
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Internal Revenue Service. Payment Plans Installment Agreements
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Internal Revenue Service. Offer in Compromise
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Internal Revenue Service. Temporarily Delay the Collection Process
20
Internal Revenue Service. Administrative Penalty Relief
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Internal Revenue Service. Penalty Relief for Reasonable Cause