The Wisconsin Department of Revenue (DOR) uses office audits and field audits to determine whether returns report the correct tax. First contact is by letter, never by email or phone. You may authorize a representative with Form A-222, Power of Attorney. If you disagree with a notice of assessment or refund, you generally appeal to DOR within 60 days, then may go to the Wisconsin Tax Appeals Commission and the courts. A Wisconsin exam is not an IRS audit, and it is not a Minnesota Revenue audit. CLAW Tax Group represents taxpayers in Wisconsin exams; Jon Call, Enrolled Agent / NTPI Fellow, leads most administrative audit work, and Matthew Wildes, JD CPA, joins when the matter needs an attorney.
Key takeaways
- Office audits are limited examinations, often by correspondence; field audits are detailed reviews of books and records.
- DOR’s first contact is never by email or phone; the audit starts with a letter.
- Representation: Form A-222 (or a notarized alternate POA that clearly authorizes tax information access).
- Appeal to DOR within 60 days of receiving the notice; missing that window can make DOR’s action final, with claim-for-refund as a later path in some cases.
- General determination window: four years from the later of the return due date or filing date, with a six-year understatement exception and no limit if no return was filed or a return was filed with intent to evade.
Parent hub: Wisconsin Department of Revenue help. Federal contrast: audit defense.
Office audit path
An office audit is a limited examination of your return. It generally covers specific issues or periods and is not a full audit of all records. The audit begins when DOR sends a letter selecting the return for review. Work is generally by correspondence; some work can be done by phone or conference. You can follow progress in My Case Manager.
After the exam, DOR sends a determination letter or notice: additional amount due, refund, or no change. Interest on an amount due generally accrues at 12% per year from when the tax was originally due (set by statute and not waivable on that basis). If returns were not filed or a notice is not timely paid, interest accrues at 18%. Refund interest accrues at 3% per year.
Agency detail: Publication 511, Office Audit of Wisconsin Tax Returns.
Field audit path
A field audit is a detailed review of returns and books and records to determine whether correct amounts were reported. Typical steps DOR publishes:
- 1. Letter notifying you the returns were selected and asking you to call to set the initial meeting. First contact is never by email or phone. The letter lists tax types and periods, auditor and supervisor contacts, and My Case Manager access.
- 2. Examination of returns and records, often at your place of business, plus possible third-party information.
- 3. Proposed report discussed in a final conference. You and/or your representative receive a complete copy and are asked to sign the Notice of Proposed Field Audit Report indicating full or partial agreement or total disagreement (generally within 30 days).
- 4. Final mail notice of assessment, refund, or no change.
If you disagree with proposed findings, tell the auditor promptly. A conference with the supervisor may resolve issues before formal appeal. Even if you signed the proposed notice indicating disagreement, you still must send a written appeal of the final notice.
Agency detail: Publication 501, Field Audit of Wisconsin Tax Returns.
Disagreeing and appealing
If you disagree with DOR changes, you may:
- Pay in full without appealing, then consider a later claim for refund of amounts paid (for many tax types other than sales and use tax, within four years of the audit notice date; sales and use tax refund claim rules differ), or
- File an appeal with DOR within 60 days of receiving the notice.
To stop further interest accumulation on amounts owed while appealing, you may deposit the entire additional assessment (including interest and penalty, if any) with DOR. Interest at 3% per year is paid on any portion of the deposit later refunded. Paying a portion you agree with is treated as an admission of that portion’s validity.
Appeal ladder
DOR lists six levels, in order:
- 1. Wisconsin Department of Revenue, Resolution Unit
- 2. Wisconsin Tax Appeals Commission
- 3. Circuit Court
- 4. Court of Appeals
- 5. Wisconsin Supreme Court
- 6. U.S. Supreme Court
An appeal to DOR must be in writing, state specific reasons and supporting documents, and be filed online, faxed, or mailed so it is actually received within 60 days, or mailed in a properly addressed prepaid envelope postmarked before midnight of the 60th day and received within five days of the 60th day. If that window is missed, DOR’s action is final and an assessment must be paid; the remaining path is often a claim for refund.
A Commission appeal must be filed within 60 days of receiving DOR’s decision. Circuit Court review of a Commission decision is generally within 30 days after the mailing date of the Commission decision.
Taxpayers may represent themselves or use a representative such as an attorney or accountant. For confidential tax information access during the audit and appeal, use Form A-222.
How far back Wisconsin can audit
Generally, returns are audited for the past four years. DOR must send a notice of field audit determination (or, for office audits, a notice of assessment or refund) within four years of the later of the income or franchise return due date or the date the return was filed.
Exceptions DOR publishes for income or franchise tax:
- Six years if you reported less than 75% of the correct taxable income and the additional tax is over $100 for that return ($200 for a joint return on the office-audit publication).
- No statute of limitations if no return was filed, or if an incorrect return was filed with intent to evade taxes.
State collection clocks (and how they differ from the IRS) are covered in Minnesota and Wisconsin collection statute clocks.
Carryforward years (NOLs, net business losses, credits) can pull earlier returns into review when those items feed the audit period. That is not the same as the common IRS three-year assessment period.
How a Wisconsin exam differs from an IRS audit (and from Minnesota)
| Topic | Wisconsin DOR | IRS / Minnesota |
|---|---|---|
| Agency and forms | Wisconsin notices; Form A-222 POA | IRS Form 2848; Minnesota REV184i / REV184b |
| Typical paths | Office (Pub 511) and field (Pub 501) | Correspondence, office, or field under federal rules; Minnesota mail or appointment model |
| First contact | Letter only; never email or phone as first contact | IRS correspondence exams also commonly open by mail; Minnesota uses mail or appointment |
| Appeal clock | Generally 60 days to DOR Resolution Unit, then Commission and courts | Federal deficiency / Appeals / Tax Court paths; Minnesota generally 60 days to Revenue or Tax Court |
| Lookback (general filed return) | Four years; six-year understatement exception; no limit if unfiled or evasion intent | Common federal three-year rules with exceptions; Minnesota generally 3½ years for filed income tax returns |
For federal audit representation, see audit defense. For a Minnesota audit, see Minnesota tax audit.
What happens if the audit becomes a bill
If the assessment becomes final and unpaid, the file can move into Wisconsin collection: tax warrants, wage attachments, bank levies, refund intercepts, and payment plans. That is a different procedure set from the exam. Bridge: Wisconsin tax levy, wage attachment, and tax warrant. Services hub: tax relief services. State index: state tax help.
How will I know Wisconsin selected me for audit?
First contact is by letter, not email or phone, per DOR Publications 501 and 511. The letter asks you to call the auditor to schedule (field) or explains the correspondence review (office).
What is the difference between an office audit and a field audit?
An office audit is a limited examination, often by correspondence, covering specific issues. A field audit is a detailed review of books and records, often at the business, with a proposed report and Notice of Proposed Field Audit Report before the final notice.
How long do I have to appeal a Wisconsin audit notice?
Generally 60 days from receiving the notice to appeal to the Department of Revenue. If you miss that window, DOR’s action can become final and payment may be required, with a claim for refund as a later path in some cases.
Can I have a representative at a Wisconsin field audit?
Yes. Auditors meet with taxpayers or representatives. Complete Form A-222 (or a notarized alternate POA that clearly authorizes tax information access) and provide it to the auditor.
What if I miss the appeal deadline?
If an appeal is not filed with DOR within the required 60-day period, DOR’s action is final. If an assessment was issued, it must be paid. The remaining path DOR describes is often to file a claim for refund of amounts paid, within the claim windows that apply to that tax type.
Talk with CLAW about a Wisconsin audit letter
If you have a Wisconsin DOR audit letter, proposed field audit report, or findings notice, contact CLAW Tax Group for a consultation before the response or appeal deadline runs. We review the notice, calendar the 60-day clock, and explain representation options. We do not promise audit outcomes or refund results.
Jon Call, Enrolled Agent / NTPI Fellow · Matthew Wildes, JD CPA when the matter needs an attorney · Twin Cities practice with Wisconsin DOR matters