How to Appeal Your Property Taxes in Wisconsin

Appealing your property taxes in Wisconsin means formally challenging the assessed value your local municipal assessor placed on your property — first informally during the "Open Book" period, then, if needed, by filing an objection with your municipality's Board of Review, and potentially appealing further to the state or circuit court. In Wisconsin you appeal the assessment (the assessor's opinion of your property's value), not the tax bill or the tax rate directly, because a lower assessed value is what lowers the taxes you ultimately owe.

What you are actually appealing

Your Wisconsin property tax is a function of two things: your property's assessed value and the local tax (mill) rate set by your taxing jurisdictions. You cannot appeal the mill rate — that is set through local budgets. What you can challenge is whether the assessor's value is accurate and fair. If your assessment is higher than what your property would realistically sell for, or higher than comparable homes are assessed for, you may have grounds to appeal.

The core question a Wisconsin Board of Review asks is whether your assessment reflects fair market value and is uniform with similar properties. Your job as the property owner is to show, with evidence, that it does not.

Know the Wisconsin appeal path

Wisconsin uses a distinctive, multi-step process. Understanding the order matters, because most later steps are only available if you complete the earlier ones.

1. Open Book

"Open Book" is an informal period, before the formal Board of Review meets, when the completed assessment roll is open for inspection and you can talk directly with the assessor. Many disputes are resolved here without a formal hearing. This is your best low-friction opportunity to point out errors and ask how your value was determined.

2. Board of Review (BOR)

The Board of Review is the formal, quasi-judicial body in your municipality that hears objections. To be heard, Wisconsin generally requires you to provide advance notice of your intent to object and to file a written objection form — and you (or a representative) typically must testify. The Board weighs your evidence against the assessor's and can raise, lower, or sustain the assessment.

3. Further appeal

If you disagree with the Board of Review's decision, Wisconsin law provides additional routes, which may include appealing to the Wisconsin Department of Revenue or to circuit court, depending on the situation. These later steps have their own procedures and deadlines.

Important: The exact windows for Open Book, for filing notice of intent, and for the Board of Review vary by municipality and by year. Do not rely on a date you read online — read the assessment notice you received and confirm dates with your local assessor or municipal clerk.

Step-by-step: how to appeal

1. Read your assessment notice carefully. Wisconsin assessors send a notice of changed assessment when your value changes. It lists your new assessed value and — critically — the dates and instructions for Open Book and the Board of Review. Treat this document as your calendar and your rulebook.
2. Confirm the property record is correct. Ask the assessor for your property record card. Check square footage, lot size, bedroom/bathroom count, condition, and any features. Factual errors (e.g., a finished basement that isn't finished) are among the easiest, strongest grounds for a correction.
3. Build your evidence. The most persuasive evidence is what comparable properties actually sold for near the assessment date, and how similar homes in your area are assessed. A recent independent appraisal, photos of defects, or contractor repair estimates can also help.
4. Attend Open Book. Meet or call the assessor, present your findings, and try to resolve it informally. Get any agreed correction in writing.
5. File your objection for the Board of Review. If Open Book doesn't resolve it, follow your municipality's instructions to give notice of intent and file the required written objection form before the stated deadline.
6. Present at the Board of Review hearing. Be concise and factual. State your opinion of value and walk through your comparable sales and any property-record errors. Stick to value and uniformity — not the size of your tax bill or your ability to pay.
7. Decide whether to appeal further. If the Board rules against you and you still disagree, review the next-level options (state agency or court) and their deadlines promptly.

Evidence checklist

• [ ] Your assessment notice (with all dates and instructions)
• [ ] Your property record card from the assessor
• [ ] 3–5 comparable sales near the assessment date, similar in size, age, and location
• [ ] Assessed values of comparable neighboring properties (for a uniformity argument)
• [ ] A recent independent appraisal, if available
• [ ] Photos and documentation of condition issues or needed repairs
• [ ] Written repair or renovation estimates, if relevant
• [ ] Your completed municipal objection form and notice of intent
• [ ] A short, written summary of your opinion of value and why

Common mistakes to avoid

• Arguing the tax rate or your tax bill. The Board reviews value, not the rate or affordability.
• Missing the notice-of-intent step. In Wisconsin, failing to give required advance notice can prevent the Board from hearing you at all.
• Bringing opinions, not evidence. "My taxes went up too much" is not evidence; comparable sales and record errors are.
• Waiting past the window. The appeal window is typically a set period tied to your notice and your municipality's schedule — verify it the day your notice arrives.
• Skipping Open Book. It is often the fastest way to fix a clear error.

When an appeal is worth it

An appeal makes the most sense when you have concrete reasons to believe your assessment overstates market value: a property-record error, comparable sales below your assessed value, or clearly higher assessments than similar neighbors. If your assessment is close to what your home would sell for, the effort may not change much. Weigh the potential tax savings against the time involved — but remember the process is designed to be usable by owners themselves, and Open Book is free.

Bottom line

To appeal property taxes in Wisconsin, verify the facts on your assessment notice, gather comparable sales and evidence of any errors, resolve what you can at Open Book, and file a timely objection with your local Board of Review — escalating further only if needed. Because deadlines and schedules differ by municipality and year, always confirm the specific dates on your own notice or with your local assessor before you act.