The deadline to file a formal objection to your 2026 City of Madison property tax assessment is May 15, 2026 at 4:30pm, under Wis. Stat. § 70.075. Objections go to openbook@cityofmadison.com. After you file, the Board of Assessors conducts an individual appraisal of your property between June and the fall. Here's the plain-English version of how the whole process works.
The deadline to file your 2026 objection is May 15, 2026 at 4:30pm. Objections are submitted by email to openbook@cityofmadison.com.
This deadline is set by Wisconsin state law and the city does not extend it. If you're considering an appeal, build in a buffer of at least a few days. Email systems fail. Attachments don't go through. The city's inbox doesn't process objections at 4:31pm.
You may have seen the term "Open Book" tossed around. Open Book is the period before the formal objection deadline when you can review the assessor's data, talk to an assessor informally, and request changes without filing a formal objection. It's worth doing if you have time, because some issues (like a wrong square footage) can get fixed without ever needing to escalate.
But Open Book conversations are optional. The objection process is the formal mechanism, and that's what locks in your right to appeal.
After you file your written objection, your case goes to the Board of Assessors. This board exists under Wis. Stat. § 70.075, which applies to cities of Madison's size. Their job is to do an individual appraisal of your property — meaning they actually look at your specific home, your evidence, and your comps, rather than relying on the mass appraisal model that produced the original number.
Board of Assessors meetings run from June through the fall. You don't pick the date — they schedule it and notify you. You don't typically need to attend in person; the board reviews the written objection and supporting evidence you submitted.
The board has three options: leave your assessment unchanged, lower it, or (in rare cases) raise it. The "raise it" outcome is uncommon and generally happens only if your objection inadvertently reveals new information that supports a higher value. For most homeowners with a legitimate case, the realistic outcomes are "no change" or "reduction."
You'll get a written decision in the mail. If your assessment is reduced, the new number flows through to your December tax bill. You're done.
If the Board of Assessors denies your objection or doesn't reduce your assessment enough, you can escalate to the Board of Review under Wis. Stat. § 70.47.
This is a more formal stage. The Board of Review is a quasi-judicial body. Hearings involve sworn testimony, the ability to cross-examine witnesses, and a more structured presentation of evidence. The standard of review is whether the assessment is supported by the evidence — and the burden generally shifts to you, the property owner, to demonstrate it isn't.
Most Madison homeowners don't need to go to the Board of Review. The Board of Assessors stage is usually where things get resolved, especially when your objection is well-documented with strong comps.
The objections that succeed at the Board of Assessors stage almost always include the same four ingredients:
A clear statement of your opinion of value — the number you think the home should actually be assessed at. Don't ask the board to "review" your assessment without proposing an alternative. Give them a target.
Three to five comparable sales from 2025. Sales close to your home, similar size, similar age, similar style. Pull them from the City of Madison Assessor's public records.
Documentation of your home's condition issues, especially anything that materially affects market value. Photos help. Contractor quotes help even more.
Corrections to the property record card if the city's data is wrong about your square footage, bedroom count, basement finish, or other features.
For most Madison homeowners, the rough timeline for a 2026 appeal looks like this. You file your objection between mid-April and May 15. The Board of Assessors schedules your individual appraisal review sometime between June and September. You get a written decision in the late summer or fall. If you accept the decision, your December 2026 tax bill reflects it. If you don't, you have a window to escalate to the Board of Review.
It's tempting to view this as bureaucratic friction, but it actually exists for a good reason. Mass appraisal is fundamentally a statistical exercise, and individual assessments can be off by as much as 20%. Wisconsin's appeal process is the legal mechanism for catching those errors. The system assumes some percentage of homeowners will push back. If you have a real case, you should be one of them.
We built a free tool that uses all 2,668 real 2025 sales records from the City of Madison Assessor. It finds the right comps for your home, walks you through condition documentation, and generates a properly formatted objection email you can send before the May 15 deadline. Use our free tool at mycitymadeeasy.com to check your assessment and build your objection in 2 minutes. No signup, no cost.