If a fire, flood or other accident leaves your Cook County home unlivable, the Assessor's reporting form says to file it within 90 days of the damage. That form asks for a cut in the assessment for the part of the year the home could not be used.
It is one of several tools. A regular appeal lowers the value while the damage is still there on January 1, and two exemptions keep the rebuilt home from raising the bill. Not everything counts: the Assessor gives no relief for ruined furniture or appliances, or for basement seepage, roof leaks or lost gutters.
Quick Answer
File the Assessor's Property Destruction Reporting Form within 90 days if the damage made the home unlivable; state law allows a reduction for the share of the year it could not be used. If the damage is still there on January 1, appeal the value with the Assessor while your township is open, or with the Board of Review, using dated photos, repair estimates, insurance adjuster reports and fire or building inspector reports. Missed windows can sometimes be fixed for past years through the Assessor's refund process (it calls it a Certificate of Error). When you rebuild, the Assessor's catastrophic-event exemption keeps up to $75,000 of added value off the bill for at least four years. The state's Natural Disaster Homestead Exemption can instead exempt the rebuild's rise in value until you sell. You cannot use both for the same event.
What damage counts
The Assessor says relief is possible when the damage is bad enough to lower the property's value. Its examples: structural damage to the foundation or walls, living-area flooring, central heating and air conditioning, electrical or plumbing systems, drywall and insulation, and mold.
It does not count personal property, which Illinois does not tax, or normal weather damage. A flood zone alone is not damage either: the Assessor's rules say FEMA flood maps are already built into land values.
Timing: January 1 and your options
Cook County values each home as of January 1. Damage after that date does not show up in that year's value on its own, so the order of steps matters.
| Situation | What to file | When |
|---|---|---|
| The home became unlivable during the year | Assessor's Property Destruction Reporting Form, for a share-of-the-year cut | Within 90 days of the damage |
| Damage is still there on January 1 | Appeal to the Assessor, then the Board of Review | While your township's window is open at each office |
| You missed those windows | Certificate of Error request for past tax years | Usually the last three tax years; the Assessor lists open years |
| The President or Governor declared Cook a major disaster area | State form PTAX-245, a disaster-area reassessment request | The Assessor says to include it with a flood appeal |
The 90-day form. State law says that when an accident destroys a building or makes it unfit to use, the owner on January 1 gets a lower assessment for the period it was unfit. Damage the owner caused on purpose does not count. The form asks for the date, a description, the square footage affected and whether the home is still in that condition. Miss the 90 days and the law allows no reduction for that period.
How a share-of-the-year cut works. For a declared disaster, state law spells out the arithmetic. Say a home was assessed at $30,000, the disaster was declared July 1, and the damaged home was worth the equivalent of $18,000 in assessed value.
- January 1 to July 1: 181 days at $30,000
- July 1 to December 31: 184 days at $18,000
- Blended assessment for the year: about $23,951, a 20% cut
These numbers are illustrative. The 90-day form works on the same share-of-the-year idea, and the Assessor sets the amounts.
Appeals while the damage is there. The Board of Review says that if fire, flood, demolition or another unforeseeable event made your property unlivable, you can appeal there. It hears only the current tax year and never charges a fee to file. The Assessor's vacancy policy allows no more than 24 months of reduction for any one casualty.
Tax year and bill year. Cook bills run a year behind. If a fire hits in March 2026, the cut for the unlivable months applies to tax year 2026, paid in 2027. If the home is still damaged on January 1, 2027, the tax year 2027 appeal shows up on bills paid in 2028. Check the Assessor's and Board's calendars for your township's dates.
The evidence file
Start it the day of the damage. The Assessor's flood guidelines, appeal rules and vacancy policy ask for:
- Dated color photos of the inside and outside, with a date stamp or the Assessor's attestation form.
- A written description of the damage, when it happened and, if rebuilding, the expected completion date.
- Insurance estimates and adjuster reports, repair estimates, contractor invoices, any FEMA claim and any federal disaster loan.
- Official reports from the fire department or a building inspector.
- Any government order or certificate, such as an evacuation or no-occupancy order or a new occupancy certificate, plus how long the home was unlivable.
- Repair permits and a vacancy and occupancy affidavit if the home sat empty.
For past years, the Assessor's 2026 guidelines say a Certificate of Error request is more likely to succeed when it shows substantial fire, flood or disaster damage, even for a year you already appealed. See refund filings versus appeals.
Rebuilding without a higher bill
A rebuilt home is often worth more than the old one. Two exemptions limit the hit. Both are for your main residence, both require rebuilding within two years, and both exclude flood-damaged homes in towns outside the National Flood Insurance Program. You can use one or the other for the same event, not both.
| Catastrophic-event exemption | Natural Disaster Homestead Exemption | |
|---|---|---|
| What it covers | Up to $75,000 of market value added by the rebuild, over the home's value before the event | The rise in the home's taxed value over the year before the disaster, measured the first year you apply |
| Size limit | The $75,000 cap | The rebuilt home can be no more than 110% of the old square footage |
| How long | Four years after the rebuild is finished and occupied, or until the next reassessment, whichever is later | The same amount every year until the home is sold or transferred; a surviving spouse who lives there keeps it |
| How to apply in Cook | A residential appeal to the Assessor with a copy of the rebuilding permit, while your township is open | State form PTAX-327, filed with the Assessor by July 1 or the date the county sets, every year |
The Assessor's disaster page lists the catastrophic-event route. State law does not limit the Natural Disaster Homestead Exemption to certain counties, but the Assessor's pages do not post its form, so call the Assessor at 312-443-7550 to ask for it. The first application is due no later than the first tax year after the rebuild is finished. The trade-off: one has a dollar cap and a time limit; the other has no dollar cap and lasts until a sale, but limits the rebuild's size and must be filed each year.
Recent Cook County floods
After the summer 2023 floods, the Assessor posted guidance on damage-based reductions and the forms to use, and the Board of Review's annual report for tax year 2023 says its commissioners worked to tell owners with severe flood damage how to qualify. The Assessor posted the same guidance after the August 16 to 19, 2025 storms and again in July 2026. Its flood guidelines say it also takes appeals at flood relief outreach events. In each case, the relief ran through the appeals, forms and exemptions above.
Where Censum fits
Censum's free property check shows whether your township's window is open and how appeals on homes like yours have fared. Censum's odds are built from public records, so they cannot see damage the county never recorded; your photos, estimates and reports make a damage case. Our guide to your two appeal windows explains the Assessor and Board stages.
The numbers behind this article
The deadlines, caps and time limits (90 days, 24 months, two years, four years, $75,000, 110%, July 1) come from the Assessor's forms, policies and guidelines and the state law below. The share-of-the-year example uses illustrative values and the state's disaster-area formula: prior assessment times days before the declaration, plus damaged value times days after, divided by 365.
FAQ
My basement flooded and ruined the furniture. Will my taxes go down?
Not for the furniture. The Assessor gives relief only for damage to the home itself, such as walls, floors in living areas, heating, wiring, plumbing, drywall or mold, and only if it lowers the value.
The fire was in March, but my township's appeal window isn't open. What do I do now?
File the Assessor's Property Destruction Reporting Form within 90 days of the fire. Then appeal the value when your township opens if the damage is still there on January 1.
Do I need a disaster declaration?
No for the 90-day form, appeals and both exemptions. The PTAX-245 disaster-area reassessment applies only after a declaration by the President or the Governor.
Does it cost anything to file?
No. County forms are free, and the Board of Review says there is never a fee to file an appeal.
Sources
- Cook County Assessor, Floods and Disaster Areas
- Cook County Assessor, Property Destruction Reporting Form
- Cook County Assessor, Guidelines for Appeals for Flood Damaged Homes
- Cook County Assessor, Guidelines for Appeals for Catastrophic Events
- Cook County Assessor, PTAX-245 Disaster Application
- Cook County Assessor, Vacancy Policy
- Cook County Assessor, Official Appeal Rules (photos, casualty vacancy, flood plain note)
- Cook County Assessor, 2026 Guidelines for Filing Appeals
- Cook County Assessor, Certificates of Error for Valuations
- Cook County Assessor, flood guidance of July 24, 2023
- Cook County Assessor, flood guidance of August 20, 2025
- Cook County Assessor, flood guidance of July 8, 2026
- Cook County Board of Review, Assessment Appeals
- Cook County Board of Review, news release on 2026 township openings (no filing fee)
- Cook County Board of Review, Annual Report, tax year 2023
- Illinois Department of Revenue, Property Tax Relief (Natural Disaster Homestead Exemption, Form PTAX-327)
- Illinois Property Tax Code, 35 ILCS 200/9-180 (destroyed or unlivable improvements; 90 days)
- Illinois Property Tax Code, 35 ILCS 200/13-5 (reassessment in disaster areas)
- Illinois Property Tax Code, 35 ILCS 200/15-173 (Natural Disaster Homestead Exemption)
- Illinois Property Tax Code, 35 ILCS 200/15-180 (homestead improvements, including rebuilding after a catastrophic event)
Sources accessed November 11, 2026.
Next step
Start your evidence file today, then check when your township's window opens. Check my property
Censum LLC is a data and analytics company, not a law firm and not a tax advisor. Censum is independent and is not affiliated with Cook County or any government agency.