An IRS proposed amount due is the agency’s calculation of extra tax it believes you owe based on a mismatch between your return and information reported by employers, banks, or other payers. It is a proposal, not a final bill. You have a limited window to agree, correct the record with documentation, or formally dispute it before the number becomes a legal assessment that triggers penalties, interest, and collection.
Figure Out Which Notice You Have
The notice number in the upper right corner of the letter decides your deadline and your rights. Two notices do most of the work here, and they are not interchangeable.
CP2000
The CP2000 is the most common notice proposing a balance. It comes from the IRS Automated Underreporter program, which compares third-party income data (W-2s, 1099s) against what you reported and generates a notice showing the proposed tax, penalties, and interest. You have 30 days from the date on the notice to respond, or 60 days if you live outside the United States.1Internal Revenue Service. Topic no. 652, Notice of Underreported Income – CP2000
A related notice, the CP2501, flags a discrepancy without proposing a dollar amount. Ignore it and the IRS typically follows up with a CP2000 that does.
Notice of Deficiency (CP3219N or Letter 531)
This is the legally decisive notice, often called the 90-day letter. The IRS issues it after you’ve disagreed with earlier proposed changes, or after you’ve failed to respond at all. You have 90 calendar days from the mailing date to file a petition with the U.S. Tax Court, or 150 days if the notice is addressed outside the country.2Internal Revenue Service. Understanding Your CP3219N Notice Filing a Tax Court petition is the only way to dispute the tax without paying it first. Miss the 90 days and the IRS assesses the tax and begins collection.
Why the IRS Says You Owe More
Matching your notice to the actual trigger is the first substantive step. Three categories cover most proposed amounts.
Unreported Income
The most frequent cause is a gap between what a payer reported to the IRS and what appears on your Form 1040. If an employer, client, bank, or brokerage filed a W-2, 1099-NEC, or 1099-INT the IRS can’t match to your return, the agency assumes you owe tax on it.1Internal Revenue Service. Topic no. 652, Notice of Underreported Income – CP2000 Sometimes you did omit the income. Sometimes the payer filed an incorrect information return. Sometimes you reported it on a line the IRS’s system didn’t look at, such as inside a Schedule C total.
Disallowed Deductions or Credits
The IRS also proposes additional tax when it questions a credit or deduction. For the Child Tax Credit, each qualifying child must have a Social Security number valid for employment, not an ITIN.3Internal Revenue Service. Child Tax Credit A home office deduction requires space used exclusively and regularly for business.4Internal Revenue Service. Topic no. 509, Business Use of Home If the IRS has information suggesting those tests weren’t met, it disallows the item and recalculates the tax.
Estimated Tax Shortfalls
Self-employed filers and others with income that isn’t withheld can face an underpayment penalty when quarterly payments fall short. The IRS calculates it from how much you underpaid, how long the underpayment lasted, and the quarterly interest rate during that period.5Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
Review the Proposed Changes Line by Line
Before you respond, compare every line in the notice against your return and your records. The notice shows exactly what the IRS used and how it arrived at the number. That’s where you decide whether the IRS is right, partly right, or wrong.
Start with income. If the notice says you didn’t report a 1099-NEC, pull the 1099 and check your return. A payment reported on a Schedule C total can be invisible to automated matching. If a payer issued a 1099 for the wrong amount, ask them for a corrected form and include a written explanation with your response.
For disputed deductions, gather receipts, invoices, bank statements, or mileage logs that prove each expense. Vague assertions won’t move the IRS. If you claimed $8,000 in business travel, you need records showing when you traveled, where, why, and what you spent. Contemporaneous records carry far more weight than anything reconstructed later.
After the review, you’ll land in one of three places:
- You fully agree. Sign the response form and pay promptly to stop additional interest and penalties.
- You partly agree. Mark which changes you accept, dispute the rest, and attach documentation for each disputed item.
- You fully disagree. Prepare a written explanation referencing the notice number and tax year, with every piece of supporting evidence attached.
How to Respond to a CP2000
Three delivery options exist. The IRS Document Upload Tool is the fastest; your CP2000 includes the access code you need, and it accepts scanned PDFs, JPGs, and PNGs.6Internal Revenue Service. Understanding Your CP2000 Series Notice You can also fax to the number on the notice, or mail to the campus address printed on it.
If you mail, use certified mail with return receipt requested. Federal law treats a document sent by certified or registered mail as delivered on the postmark date, which protects you if the IRS later claims it arrived late or not at all.7Office of the Law Revision Counsel. 26 USC 7502 – Timely Mailing Treated as Timely Filing and Paying Certain IRS-approved private delivery services (FedEx and UPS options) also qualify. Keep the receipt and return card with your tax records.
Your package should include the signed response form from the notice (or a written statement if you disagree), supporting documents organized by line item, and a copy of the notice itself. Send photocopies, not originals. On a joint return, both spouses generally need to sign.
If you agree and want to pay with your response, use IRS Direct Pay or send a check or money order payable to the United States Treasury. On the check, write the tax year, the related form or notice number, and your Social Security number.8Internal Revenue Service. Pay by Check or Money Order
If You Need More Time
If 30 days isn’t enough to pull records together, call the IRS Automated Underreporter Unit at the number on the notice and ask for an extension. The IRS typically grants one additional 30 days. Call at least a week before your original deadline, and follow up any phone-granted extension with written confirmation by certified mail. Don’t expect more than one extension on a CP2000.
Penalties and Interest Baked Into the Number
The proposed balance almost always includes more than tax. Some of these charges can be reduced or eliminated if you act.
Accuracy-Related Penalty
If the understatement resulted from negligence or is “substantial,” the IRS can add a penalty of 20% of the underpaid amount.9Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments For most individuals, “substantial” means the understatement exceeds the greater of 10% of the tax that should have been shown or $5,000. You can avoid the penalty by showing reasonable cause and good faith.
Failure-to-Pay Penalty
Once tax is assessed and unpaid, a penalty of 0.5% of the unpaid balance accrues each month, capped at 25%.10Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax It climbs to 1% per month after a notice of intent to levy. It drops to 0.25% per month while an installment agreement is in effect.11Internal Revenue Service. Topic no. 653, IRS Notices and Bills, Penalties and Interest Charges
Interest
Interest compounds daily from the original due date of the return until full payment. The IRS sets the rate quarterly at the federal short-term rate plus three points. For 2026, the individual underpayment rate started at 7% in the first quarter and dropped to 6% in the second.12Internal Revenue Service. Quarterly Interest Rates Interest can only be abated in narrow circumstances involving IRS errors or delays.
First-Time Penalty Abatement
If your prior three tax years are clean (all required returns filed, no penalties), you may qualify for first-time abatement of failure-to-file and failure-to-pay penalties.13Internal Revenue Service. Administrative Penalty Relief Call the number on your notice to request it. No special form or wording required; the IRS checks your account and applies relief if you qualify.
If You Agree but Can’t Pay
Agreeing doesn’t require writing a check for the full balance today. Choosing a payment option early keeps the account out of liens and levies.
Short-Term Plan
If you can pay within 180 days, you can set up a short-term plan with no setup fee. Interest and the failure-to-pay penalty still run. You can apply online if your combined tax, penalties, and interest are under $100,000.14Internal Revenue Service. Payment Plans; Installment Agreements
Monthly Installment Agreement
If you owe $50,000 or less combined and have filed all required returns, you can apply online for a streamlined installment agreement without submitting detailed financial statements.15Internal Revenue Service. Online Payment Agreement Application Setup fees run from $22 for direct-debit agreements applied for online up to $178 for non-direct-debit agreements requested by phone or mail. Low-income taxpayers may qualify for reduced or waived fees.14Internal Revenue Service. Payment Plans; Installment Agreements The failure-to-pay rate drops to 0.25% per month while the agreement is active.
Offer in Compromise
An Offer in Compromise settles a tax debt for less than the full amount when you genuinely cannot pay it all. The IRS evaluates your assets, income, expenses, and future earning potential to set your “reasonable collection potential,” and generally won’t accept an offer below that figure.16Internal Revenue Service. Topic no. 204, Offers in Compromise You must have filed all required returns and made current-year estimated payments. If you could pay through an installment agreement, you typically won’t qualify.
Currently Not Collectible
If paying anything would prevent you from covering basic living expenses, you can ask the IRS to place your account in “currently not collectible” status.17Internal Revenue Service. Temporarily Delay the Collection Process You’ll complete a Collection Information Statement (Form 433-F or 433-A) documenting your finances. Penalties and interest keep running and the IRS may file a federal tax lien, but active collection pauses.
If You Still Disagree
IRS Independent Office of Appeals
Before anything reaches court, the IRS Independent Office of Appeals offers a chance to settle administratively. Appeals operates separately from the examination and collection divisions and is empowered to weigh the risk of losing in court, which often produces compromises an examiner wouldn’t offer.18Internal Revenue Service. Appeals – An Independent Organization Follow the instructions on your notice or submit a written protest.
U.S. Tax Court
Once you have a Notice of Deficiency, you can file a petition with the U.S. Tax Court within 90 days of the mailing date (150 if addressed outside the U.S.). The filing fee is $60, waivable for inability to pay.19United States Tax Court. Guidance for Petitioners: Starting a Case This is the only venue where you can dispute the tax without paying first. If the disputed amount (including penalties) is $50,000 or less for any single tax year, you can elect the small tax case procedure, with simpler rules, relaxed evidence standards, and trials in more locations.20United States Tax Court. Case Procedure Information Small case decisions cannot be appealed by either side.
Appeals can still work with you to settle after you’ve petitioned. Most Tax Court cases resolve that way without reaching a judge.
Pay and Sue for Refund
If the 90-day window closes without a petition, the IRS assesses the tax and the Tax Court door is shut. The remaining route is to pay the full amount, file a refund claim on Form 1040-X, and if the IRS denies the claim or doesn’t act within six months, sue in U.S. District Court or the U.S. Court of Federal Claims. This path costs more up front but can be worthwhile when a particular court has favorable precedent.
Joint Returns: Innocent Spouse Relief
A proposed amount on a joint return creates joint liability. The IRS can collect the whole balance from either spouse. If the problem traces to your spouse’s errors or omissions and you didn’t know, you may be able to limit your liability by filing Form 8857. The IRS evaluates three types of relief from a single application:21Internal Revenue Service. Innocent Spouse Relief
- Innocent spouse relief, when your spouse understated taxes on the joint return and you had no knowledge of the errors.
- Separation of liability, available if you’re divorced, legally separated, or no longer living with your spouse, limiting you to your share of the understated tax.
- Equitable relief, a catch-all when the other two don’t apply but holding you responsible would be unfair.
For equitable relief, the IRS weighs factors including whether you’d face economic hardship, whether your spouse was deceptive, your involvement in household finances, and your financial expertise.22Internal Revenue Service. Equitable Relief You don’t have to choose which type fits. One application triggers review of all three.
When to Bring in Help
Many CP2000 notices are routine mismatches you can handle with your own records. Some situations call for a professional: large proposed balances, multiple tax years, business income or complex deductions, or any Notice of Deficiency. An enrolled agent, CPA, or tax attorney can represent you before the IRS directly. File Form 2848 (Power of Attorney and Declaration of Representative) to authorize them to inspect records, respond on your behalf, and sign agreements.
If you’re facing financial hardship from the proposed assessment, or the IRS has sat on your response more than 30 days past its normal timeframe, the Taxpayer Advocate Service may be able to step in at no cost. TAS is an independent organization inside the IRS that helps taxpayers with economic harm, immediate threats of adverse action, or systems that aren’t working as they should.23Taxpayer Advocate Service. Can TAS Help Me With My Tax Issue Reach them at 877-777-4778 or through a local Taxpayer Advocate office.