IRS Form 886-A, titled Explanation of Items, is the written narrative an IRS examiner attaches to an audit report to justify proposed changes to your tax return. It is not a bill and not a final assessment. It is the government’s argument for why your reported numbers should change, and it arrives with a 30-day letter that starts the clock on your response.
What Form 886-A Actually Is
You will not receive an 886-A on its own. It comes bundled with Form 4549, Income Tax Examination Changes, which lists the dollar figures of every proposed adjustment.1Internal Revenue Service. Audits by Mail – What to Do Think of Form 4549 as the spreadsheet and Form 886-A as the essay. In a correspondence audit, both forms arrive by mail. In a field audit, they show up in the Revenue Agent’s Report.
The cover letter is the 30-day letter. It gives you 30 days from the date on the letter to agree with the changes or request an appeal with the IRS Independent Office of Appeals.2Internal Revenue Service. Letters and Notices Offering an Appeal Opportunity That clock runs from the letter’s date, not the day the envelope lands in your mailbox. Open IRS mail the day it arrives.
Ignoring the package does not make the 886-A go away. If you do nothing within 30 days, the IRS will issue a Statutory Notice of Deficiency, the 90-day letter, which sets a separate and much stricter deadline for going to Tax Court.
How the Explanation Is Organized
Every 886-A follows the same four-part structure for each item the examiner is challenging. If the IRS is disputing three items on your return, you will see three separate write-ups, each with its own facts, law, analysis, and conclusion. Read each one as a self-contained argument that needs its own response.
Facts
The first part lays out the evidence the examiner relied on: bank statements, invoices, canceled checks, interview notes, third-party records like 1099s. Check every factual statement against your own records. If the examiner says you bought a rental property in 2022 and your closing documents say 2020, every conclusion built on that date is vulnerable. Factual errors are the cheapest points to win because they need no legal argument, only proof.
Applicable Law
Next comes the legal authority. A disallowed business expense will usually cite Internal Revenue Code Section 162, which allows deductions for ordinary and necessary expenses of running a trade or business.3Office of the Law Revision Counsel. 26 U.S. Code 162 – Trade or Business Expenses Unreported income cases cite Section 61, which defines gross income as income from any source.4Office of the Law Revision Counsel. 26 U.S. Code 61 – Gross Income Defined You may also see Treasury Regulations or court decisions cited.
You do not need to memorize the code. You need to know the legal test the examiner is applying so you know what evidence answers it. If Section 162 is cited and the examiner says your costs were personal rather than business, the fight is over whether the costs were ordinary and necessary for your trade. That tells you exactly what documentation to pull together.
Analysis and Discussion
This is where the examiner connects the facts to the law and explains why an adjustment follows. A typical passage: the taxpayer claimed $14,000 in vehicle expenses but provided no mileage log or receipts, so under the substantiation requirements the expenses are disallowed.
Read this section adversarially. Did the examiner ignore documentation you actually turned over? Apply the wrong test? Jump to a conclusion, for instance treating every cash deposit as unreported income without considering that you sold personal property? Analysis is where IRS positions are usually weakest, because the examiner has to reason from facts to a conclusion and reasoning can be attacked.
Conclusion and Adjustment
The last part states the dollar change to your taxable income for each year at issue. That number flows to Form 4549, which then calculates the additional tax. Check the arithmetic. If the examiner disallowed depreciation under Section 168, verify the recalculated basis and recovery period.5Office of the Law Revision Counsel. 26 U.S. Code 168 – Accelerated Cost Recovery System Computational errors are common on depreciation conventions and basis calculations. Right analysis plus wrong math still produces a wrong bill.
Your Three Response Paths
The 30-day letter gives you three options. Doing nothing is a fourth, and it has real consequences.
Agree and Sign
If the adjustments look correct, or the amounts are small enough that fighting is not worth it, you can sign Form 4549 and return it to the address on the transmittal letter. Signing waives your right to take these adjustments to the Office of Appeals or to Tax Court. The IRS will process the changes and send a bill for the additional tax, interest, and any penalties.
If you cannot pay in full, request an installment plan on Form 9465 at the same time you send back the signed agreement.6Internal Revenue Service. About Form 9465, Installment Agreement Request Don’t wait for the bill.
Request an Appeal
If you disagree with some or all of the findings, request a conference with the IRS Independent Office of Appeals. Most disputes get resolved here. Appeals officers weigh the hazards of litigation, meaning how likely the IRS is to win in court, and they can settle for less than the full proposed amount.
How you file depends on the dollars at stake. If the total proposed tax and penalties for each tax period is $25,000 or less, use Form 12203, Request for Appeals Review, a short form listing what you disagree with and why. Above $25,000 for any period, the IRS requires a formal written protest containing your name, address, and taxpayer ID; a statement that you want to appeal; the tax years involved; the specific adjustments you disagree with; the facts supporting your position; the legal basis for your position; and a declaration under penalties of perjury that the facts are true.7Internal Revenue Service. Preparing a Request for Appeals
Filing the protest holds off the Notice of Deficiency while your case sits in Appeals. Interest keeps running, but liens and levies are not on the table while the appeal is pending.
Let the 30 Days Expire
If you do not sign and do not protest, the IRS issues a Statutory Notice of Deficiency.8Internal Revenue Service. Internal Revenue Manual – Statutory Notices of Deficiency You then have 90 days from the mailing date, or 150 days if the notice is addressed to you outside the United States, to file a petition with the U.S. Tax Court.9Office of the Law Revision Counsel. 26 U.S. Code 6213 Saturdays, Sundays, and legal holidays in the District of Columbia do not count if they land on the last day.
The Tax Court cannot extend this deadline. The court itself says so plainly: “By law, the Tax Court cannot extend the time for filing a petition.”10United States Tax Court. Guidance for Petitioners – Starting a Case Miss the 90 days and you can no longer challenge the deficiency before paying. Your only remaining path is to pay in full and then sue for a refund in federal district court or the Court of Federal Claims, which is expensive and slow.
Filing a Tax Court petition costs $60, with a fee waiver available.11United States Tax Court. Court Fees If the disputed amount, including penalties, is $50,000 or less for any single year, you can elect the small tax case procedure. It is simpler and less formal, but the decision cannot be appealed by either side.12United States Tax Court. Case Procedure Information
Penalties Riding Along
The 886-A often proposes an accuracy-related penalty under Section 6662, set at 20% of the underpayment attributable to negligence or a substantial understatement of income.13Office of the Law Revision Counsel. 26 U.S. Code 6662 – Imposition of Accuracy-Related Penalty on Underpayments On a $30,000 underpayment, that adds $6,000 before interest.
Penalties are not automatic. You can challenge them by asserting reasonable cause, meaning you acted in good faith and had a legitimate reason for the position you took. The IRS looks at the complexity of the issue, your efforts to report correctly, and whether you relied on a competent tax advisor who had all the relevant information.14Internal Revenue Service. Penalty Relief for Reasonable Cause Documented reliance on a CPA or enrolled agent who advised on the exact position now being challenged is one of the strongest defenses available.
Interest Keeps Running
Interest starts from the original due date of the return, not from the date of the 886-A or the date you get a bill. For the first quarter of 2026, the IRS charges individuals 7% per year on underpayments, compounded daily.15Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 The rate adjusts quarterly.
Unlike penalties, interest is statutory and generally cannot be reduced because you have a good explanation. The IRS can abate interest only where the interest accrued because of an unreasonable error or delay by an IRS employee performing a procedural or administrative task.16Internal Revenue Service. Interest Abatement If the IRS lost your file for eight months, you have an argument for abating interest attributable to that delay. A long audit with complex issues does not qualify.
Interest continues to accrue during Appeals and while a case sits in Tax Court. That is the hidden cost of fighting. If you are confident you owe at least some of the proposed amount, making a partial payment stops interest from compounding on that portion.
If You Already Missed the Audit
If you never got the report, moved without updating your address, or failed to respond to a correspondence audit, you may still have a path back in through audit reconsideration. The IRS considers reconsideration when you have new documentation that was not previously reviewed, when you filed a return after the IRS prepared a substitute return for you, or when there was a computational or processing error.17Internal Revenue Service. Audit Reconsideration
Gather your new supporting documents, attach them to a letter identifying the adjustments you dispute and why, and mail the package to the IRS. Form 12661, Disputed Issue Verification, is the recommended form for laying out the contested items clearly.17Internal Revenue Service. Audit Reconsideration Include a copy of the original Form 4549 if you have it, and send photocopies only. The IRS will not return originals.
Reconsideration is not available if you already signed an agreement accepting the assessment, if a court has issued a final determination on your liability, or if you have already paid the full amount, in which case your remedy is an amended return on Form 1040-X.18Taxpayer Advocate Service. Audit Reconsiderations
When to Bring in a Representative
Three types of professionals have full authority to represent you before the IRS at every stage — examination, appeals, and collections: attorneys, certified public accountants, and enrolled agents.19Internal Revenue Service. Power of Attorney and Other Authorizations Enrolled agents are federally licensed tax specialists and often cost less than attorneys with the same representation rights. To authorize any of them, file Form 2848, Power of Attorney and Declaration of Representative.20Internal Revenue Service. Instructions for Form 2848, Power of Attorney and Declaration of Representative
The right time to engage someone is when the 886-A arrives, not after you have already responded or blown a deadline. Practitioners who handle these cases regularly spot weaknesses in the examiner’s analysis that most taxpayers miss and know how Appeals officers weigh a file. When the proposed deficiency is large enough that the tax, penalties, and interest could cause real hardship, representation usually pays for itself in a reduced assessment.