IRS Form 4549-A, “Income Tax Examination Changes,” is the report a revenue agent issues after auditing a flow-through entity such as an S corporation, trust, or partnership that stayed outside the centralized partnership regime. It lays out proposed adjustments to the entity’s income, deductions, and credits, and because those items pass through to owners, it tells you what the agent believes you now owe on your personal return. It is a proposal, not a bill. Signing it or declining to sign it is the decision that controls every option you have afterward.
What’s on the Form
The layout is straightforward. The top identifies the taxpayer, the entity, the tax periods examined, and the return type. The body is a three-column comparison: amounts “As Reported,” the agent’s proposed “Adjustments,” and the resulting “Corrected” figures. Schedule A covers income adjustments, Schedule B covers deduction and credit adjustments, and each line cites the Code section the agent relied on.
The computation section converts the corrected income into a proposed deficiency, adds any proposed penalties, and notes that interest will accrue. None of it is assessed yet.
The document that actually tells you whether the agent is right is Form 886-A, Explanation of Items, which usually accompanies the 4549-A.1Internal Revenue Service. Internal Revenue Manual 4.10.8 – Report Writing The 886-A sets out the facts the agent found and the legal authority cited for each change. Read it closely before deciding anything. Then check the arithmetic on your own K-1 allocation; applying the wrong ownership percentage is a surprisingly common error.
What Signing Actually Does
The signature line on Form 4549-A is a written waiver of the restrictions on assessment under IRC 6213.2Office of the Law Revision Counsel. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court By signing, you give up two things at once: your right to receive a formal Notice of Deficiency, and your right to petition the U.S. Tax Court before paying.
That is why the decision matters more than the form looks like it should. Everything downstream, the appeal, the mediation, the day in Tax Court, exists only if you have not signed.
If You Agree
Sign the form and return it by the deadline shown. The IRS will assess the deficiency and send a Notice and Demand for Payment, which is the actual bill. Interest keeps running from the original due date of the return until you pay in full. You avoid further professional fees and the matter closes quickly, but you lose every opportunity to negotiate the amount.
Agreement makes sense when the agent’s position is clearly correct, when the deficiency is small, or when the cost of fighting would exceed any realistic reduction.
If You Disagree: The 30-Day Letter and Protest
Do not sign. The IRS will issue a 30-day letter (Letter 525, Notice of Proposed Deficiency), which opens your window to protest in writing to the IRS Independent Office of Appeals.3Taxpayer Advocate Service. Letter 525 Audit Report/Letter Giving Taxpayer 30 Days to Respond You have 30 days from the date of that letter to send the protest to the IRS address shown on it, not to Appeals directly. Miss the window and the IRS skips Appeals entirely, issuing the Statutory Notice of Deficiency instead.
A formal written protest must include:4Internal Revenue Service. Preparing a Request for Appeals
- Your name, address, taxpayer identification number, and the tax periods involved
- A statement identifying each specific adjustment you contest
- The facts supporting your position
- The law or authority you rely on
- A signed declaration under penalties of perjury that the facts are true and correct
If the total proposed tax and penalties for each period is $25,000 or less, you can file a Small Case Request instead, which is a brief letter identifying what you disagree with and why.
Once Appeals accepts the case, an Appeals Officer reviews the file independently and has settlement authority. The Officer can weigh the “hazards of litigation,” meaning the realistic odds the IRS would win in court, and settle for less than the full proposed amount. Many flow-through disputes resolve here.
Fast Track Settlement
Before accepting the 30-day letter route, ask the examining agent about Fast Track Settlement. It is a voluntary mediation program where an Appeals Officer sits as neutral mediator between you and the agent, with a target of resolving the matter within 60 days for individuals and small businesses, 120 days for large businesses.5Internal Revenue Service. Fast Track You and the agent jointly submit Form 14017 to apply.
All issues must be fully developed, meaning fieldwork is finished and documentation is in. The mediator can propose terms but cannot force either side to accept. If Fast Track does not resolve the dispute, your right to file a traditional protest stays intact.6Internal Revenue Service. Publication 5022 – Fast Track Settlement For a flow-through audit that comes down to the legal treatment of a handful of items, this can save months.
The 90-Day Letter and Tax Court
If Appeals cannot settle, or you missed the 30-day window, the IRS issues a Statutory Notice of Deficiency, commonly called the 90-day letter. From the date on that notice you have 90 days to file a petition with the U.S. Tax Court, or 150 days if you are outside the United States.2Office of the Law Revision Counsel. 26 USC 6213 – Restrictions Applicable to Deficiencies; Petition to Tax Court The deadline is absolute.
Tax Court is the only forum where you can challenge the deficiency without paying first.7Internal Revenue Service. Understanding Your CP3219N Notice Miss the 90 days and the IRS assesses the tax and starts collection; your only remaining route is to pay in full and sue for a refund in federal district court or the Court of Federal Claims. For a sizable deficiency, that prepayment barrier is often why taxpayers decline to sign the 4549-A in the first place.
Penalties and Interest on Top
Two additions typically swell the amount above the raw deficiency.
Accuracy-Related Penalty
The most common addition is the 20% accuracy-related penalty under IRC 6662, which applies to any portion of an underpayment caused by negligence, disregard of rules, or a substantial understatement of income tax.8Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments A substantial understatement means the understatement exceeds the greater of 10% of the correct tax or $5,000. For taxpayers claiming the qualified business income deduction under Section 199A, the threshold is 5%.
You can defeat the penalty by showing reasonable cause and good faith, substantial authority for the position, or adequate disclosure on the return. Raise these defenses in your protest.
Interest
Interest runs from the original due date of the return until paid in full, at the federal short-term rate plus three percentage points, compounded daily.9Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 For the first quarter of 2026, the individual underpayment rate is 7%; for the second quarter, it is 6%.10Internal Revenue Service. Internal Revenue Bulletin 2026-8
Interest, unlike penalties, is not negotiable. Appeals cannot waive or reduce it. Every month the dispute continues, interest grows. On a deficiency from a return filed several years back, interest alone can rival the original tax.
Check the Statute of Limitations
Before investing in a protest, check whether the IRS can still assess. The ordinary limitations period is three years from the date the return was filed.11Internal Revenue Service. Time IRS Can Assess Tax Important exceptions:
- If the return omits more than 25% of gross income, the period expands to six years.12Office of the Law Revision Counsel. 26 USC 6501 – Limitations on Assessment and Collection
- For fraud or failure to file, there is no limit.
- If you signed a statutory waiver extending the deadline, the extension controls. You were not required to sign, but refusal often prompts the agent to issue a report based on incomplete information.
If the deadline has already passed, the IRS cannot legally assess the tax no matter what the 4549-A says. This defense gets overlooked, especially in long-running entity exams where the individual owner’s statute may expire on a different date than the entity’s.
Your State Return Will Follow
A final federal adjustment does not stay federal. Most states with an income tax require you to report federal changes and amend the state return within a set window after the federal adjustment becomes final. Deadlines run from 90 days to two years depending on the state. Missing that notification can draw separate state penalties and extend the state assessment period. Do not assume the state will learn through information sharing; matching varies widely and the filing obligation is yours.
If You Already Signed: Audit Reconsideration
Signing is not always the end. You can request audit reconsideration if you filed the original return, the assessment is unpaid (or involves disputed credit reversals), and you have information the agent did not consider.13Internal Revenue Service. Internal Revenue Manual 4.13.1 – Examination Audit Reconsideration Process Reconsideration is not a second argument on the same facts, and the IRS will not reopen matters closed by a closing agreement, a compromise, or a Tax Court decision. But if you locate records substantiating the exact deduction the agent disallowed, send the request with the documentation to the office that handled the original exam.
One Boundary: BBA Partnerships Do Not Get a 4549-A
If you are a partner in a partnership subject to the centralized audit regime under the Bipartisan Budget Act of 2015, you will not receive a Form 4549-A at all. Under that regime, the IRS assesses and collects any resulting tax at the partnership level, and the partnership either pays or makes a push-out election under IRC 6226 that shifts the adjustments to partners.14Office of the Law Revision Counsel. 26 USC 6225 – Partnership Adjustment by Secretary15Internal Revenue Service. BBA Partnership Audit Process Partnerships with 100 or fewer eligible partners can elect out, and those that do, along with S corporations and trusts, continue to receive Form 4549-A at the entity level.16Internal Revenue Service. Elect Out of the Centralized Partnership Audit Regime If a 4549-A is in your hands, you are in the traditional process described above.