How a Three-Year IRS Audit Gets Resolved: Substantiation, the 30-Day Letter, and Appeal Rights

A client of ours — a CPA practicing in Texas — claimed a tax credit on an amended return. The IRS disallowed it, then opened an examination covering three tax years: 2017, 2020 and 2021, asking for substantiation of essentially everything on those returns. Here is how a three-year IRS audit of that kind actually gets worked, and where in the process a taxpayer’s leverage sits.

The situation

An amended return claiming a credit is a return the IRS looks at twice: the original filing was already processed, and the amendment asks the service to revisit it and pay money out. When the credit was disallowed the file did not close — the examination function picked it up and expanded the scope to two more years, requesting substantiation for expenses, credits, income, capital gains and losses.

That expansion is what most taxpayers do not expect: an issue on one return is often the reason a second and third year get pulled in, because the IRS wants to know whether the same treatment was applied elsewhere. Our client kept meticulous books — but having records and assembling a line-by-line response to a multi-year document request are two different jobs, and the second is full-time work for weeks.

Why it was serious

• The scope was open-ended. A request covering income, expenses, credits and capital transactions across three years is not a single-issue audit — every line is in play until it is substantiated.
• Silence has a default outcome. An examination that gets no response does not stall; it proceeds to a proposed assessment, and the taxpayer inherits a balance due to fight from behind.

The options, and why we chose substantiation

There were three realistic paths: concede the credit and negotiate the resulting balance; substantiate the easy items and let the contested credit go; or substantiate the whole file and argue the credit on the merits.

Collection-side routes — an installment agreement, an offer, currently not collectible status — only become relevant once a liability exists. They manage a debt; they do not contest whether it is correct. Where the records genuinely support the return, conceding first and negotiating later gives away the strongest argument available. Here the documentation existed and was organized, which made full substantiation the right route — and the one that settles the question at the cheapest stage.

How an IRS examination actually works, step by step

1. The notice arrives by mail — and only by mail

The IRS states plainly that if an account is selected for audit it notifies the taxpayer by mail, and that it will not initiate an audit by telephone. Audits are conducted by mail or by in-person interview, at an IRS office or at the taxpayer’s place of business. Anyone phoning to announce an audit is not the IRS.

2. The document request is written and specific

The IRS provides a written request for the specific documents it wants to see. That request is the map for the whole engagement, and it also sets the boundary: items outside it have not been raised, and volunteering material beyond what was asked can widen an examination rather than close it.

On scope, the IRS generally audits returns filed within the last three years and says it usually does not go back more than six. The underlying assessment period is generally three years after a return is due or was filed, whichever is later — which is also why the IRS asks taxpayers to keep records for at least three years from the filing date.

3. The response is built around the return, not around the question

This is the step that did the work here. A pile of receipts is not substantiation. What persuades an examiner is a reconciliation: each figure on the filed return traced to the ledger, the ledger to the bank, the bank to the source document — so the examiner can follow any single number from the return down to the invoice without reconstructing anything.

For the disallowed credit, the argument had two halves that must be made separately: that the taxpayer met the credit’s eligibility conditions, and that the amounts claimed were supported by records. A credit fails if either half is missing, and examiners routinely disallow on the half the taxpayer did not address.

How long this takes varies. The IRS attributes the length of an audit to its type, the complexity of the issues, the availability of the information requested, and the availability of both parties to schedule. Representation controls exactly one of those four: the availability of the information.

4. The examination closes one of three ways

An audit ends as no change, agreed (the taxpayer accepts the proposed changes), or disagreed. Which of the three doors a file goes through is largely determined by the quality of what was submitted at step three.

5. Disagreeing: the 30-day letter and the Independent Office of Appeals

If the examiner proposes changes the taxpayer disputes, the IRS issues a letter with a computation report of the proposed adjustments and an invitation to appeal. Letter 525 is the general 30-day letter; Letter 915 transmits an examination report; Letter 950 is used for unagreed deficiency cases. Each carries a window to file a protest — generally 30 days from the date of the letter, though Letter 692, which requests consideration of additional findings, runs on a shorter 15-day window. The deadline printed on the letter governs.

The route the protest takes depends on size. Where the entire amount of additional tax and penalty proposed for each tax period is $25,000 or less, the taxpayer can file a small case request on Form 12203, Request for Appeals Review. Above that, a formal written protest is required; Publication 5 sets out what it must contain. Either way, the request goes to the IRS address on the letter that explains the appeal rights — not directly to Appeals, which only delays it.

The Independent Office of Appeals exists to resolve disputes without litigation, fairly and impartially to both sides. Before that stage, a conference with the examiner’s manager and IRS mediation are also available. Publication 1 sets out the right to appeal disagreements within the IRS and before the courts.

6. The hard deadline at the end: the notice of deficiency

If the dispute is not resolved, the IRS issues a statutory notice of deficiency, such as a CP3219A. It carries a 90-day period in which to petition the U.S. Tax Court, and the IRS cannot extend it — the notice says expressly that continuing to work the issue during those 90 days does not extend the petition deadline. Form 5564 is the reply form. If no petition is filed, the IRS assesses the proposed changes and sends a bill, and the argument shifts from whether the tax is owed to how it will be paid.

That is why the substantiation stage matters: every door downstream is narrower and shorter-fused than the one before it.

What changed for the client

We prepared the audit response and argued that the expenses were substantiated and the credit should be allowed. Because the records were complete, every disputed figure tied back to source documentation. The examination closed with the credit restored and a refund due rather than a balance owed — the file reversed direction at the examination stage, with no protest, Appeals conference or Tax Court petition.

The client went from an open three-year examination with an open-ended document request to a closed file — no assessment to negotiate, nothing carried into collections. That outcome turned on the records in this case. Every examination is decided on the taxpayer’s own facts and the IRS’s determination, and a different file with different documentation would land somewhere else.

What to do first if you are in the same position

1. Find the date printed on the letter, not the postmark. Appeal windows generally run 30 days from it; some run 15. A notice of deficiency runs 90 days and cannot be extended.
2. Treat the written document request as a list and answer only that list — everything asked for, nothing beyond it.
3. Check whether your records reconcile before you decide to fight. If the return ties to the ledger and the ledger to the bank, substantiation is the strongest route. Gaps are worth finding before a position is taken, not after.
4. Get representation before the response goes out, not after the 30-day letter arrives. That response is the cheapest point of leverage in the process.

Outcomes in any examination depend on the taxpayer’s specific facts, the quality of the records and the IRS’s determination. Nothing here predicts any other case, and nothing here is tax or legal advice for your situation.

Sources

• IRS Audits
• IRS Independent Office of Appeals
• Preparing a Request for Appeals
• Letters and Notices Offering an Appeal Opportunity
• Understanding Your CP3219A Notice