How to Challenge Your 2026 Ontario Property Assessment — and Why Your Tax Bill Rose Even Though Your Value Didn't

AP Bains | CENTURY 21 Green Realty Inc. Brokerage

A 2026 property assessment notice can trigger two practical questions fast. “My assessment notice says nothing changed, so why is my tax bill higher?” and “How do I challenge it if I think the number is wrong?”

A separate article on this site explains why your assessment differs from what your property is actually worth in today's market.

Why your bill rose with a frozen assessment

Black-and-gold infographic showing assessed value multiplied by municipal tax rate equals property tax, with 2026 Peel, Caledon, and Brampton figures

The basic calculation is:

Assessed value × municipal tax rate = property tax

If your assessed value does not change but the municipal tax rate rises, your property tax bill can rise.

Your total bill is also made up of several components. Depending on where you live, it combines regional taxes, local municipal taxes, and education taxes. That means a municipal headline percentage is never the entire story.

For 2026:

  • The Region of Peel approved an overall property tax increase of 4.20%. This included 2.16% for Peel Regional Police, 1.98% for regional services, and 0.06% for other agencies.
  • Peel also implemented a 7.8% water and wastewater utility rate increase.
  • The Town of Caledon approved a total municipal tax increase of 3.27%, made up of a 2.27% property tax increase for operating costs and a 1% infrastructure levy.
  • The City of Brampton approved a 0% increase for core municipal services, plus an additional 1% tax levy dedicated to the Peel Memorial hospital project.

These figures come from the applicable 2026 budget and tax-policy documents issued by the Region of Peel, Town of Caledon, and City of Brampton.

The two facts that make a challenge worth considering

First, 2026 is not a province-wide reassessment year, so for most properties the assessment basis is unchanged from 2025.

Second, MPAC can still review and revise a property record in a non-reassessment year. That can happen because of new construction, an addition or significant renovation, a demolition or removed structure, a change in use or classification, a change to ownership or legal description, a change in school support, or a correction to recorded details.

That means errors and outdated property details are the realistic grounds for a challenge, not general market movement. Current 2026 sale prices do not automatically prove that a 2016-based assessment was wrong, because the evidence must relate to the legislated valuation basis.

How to challenge your assessment, step by step

Step-by-step infographic showing review notice, file Request for Reconsideration with MPAC, receive decision, and appeal to the Assessment Review Board within 90 days

For residential, farm, managed forest, and conservation land properties, you must file a Request for Reconsideration, or RfR, with MPAC before you can appeal to the Assessment Review Board. You cannot go straight to the ARB.

1. Review your notice

Confirm your property classification, legal description, building details, and listed improvements. Your deadline is printed on your Property Assessment Notice.

2. File an RfR with MPAC

You can file online through AboutMyProperty or by mail, but file by the deadline printed on your notice.

Use AboutMyProperty to compare how similar properties are described and assessed. For the property types above, the RfR is the required first step.

3. Gather evidence that fits the process

Your evidence should either relate to the January 1, 2016 valuation basis or show that MPAC’s property information is incorrect.

Useful documents may include:

  • Comparable property information.
  • Photos showing condition or removed structures.
  • Building permits.
  • Surveys and legal descriptions.
  • Floor plans and measurements.
  • Information about additions, renovations, demolitions, or use.

Current 2026 sale prices do not automatically prove that a 2016 assessment was wrong. The evidence must be relevant to the legislated valuation basis.

4. Review MPAC’s written decision

If you agree with MPAC’s decision, sign the Minutes of Settlement. MPAC forwards it to the municipality for processing.

5. Appeal to the ARB if needed

If you still disagree, you may appeal to the Assessment Review Board within 90 days of the mailing date on MPAC’s RfR decision. The RfR decision must be received before filing with the ARB.

Use Tribunals Ontario’s Assessment Review Board resources for the current forms, process, filing fees, and e-File instructions. Tribunals Ontario’s e-File service provides a $10 discount on the filing fee. You will need your Property Assessment Notice, your RfR decision letter where applicable, and a credit card for the fee.

For commercial, industrial, and other non-residential property types, you may file an RfR with MPAC or appeal directly to the ARB. Direct ARB appeals generally use a March 31 deadline for annual assessments or 120 days from the notice date for other assessment types.

If you missed an RfR deadline because of extenuating circumstances, you may apply to the ARB for an extension using the Request for Reconsideration Extension of Time Form. Supplementary and omitted assessments have their own deadline printed on the applicable notice.

You do not need to pay a consultant

You can represent yourself. The RfR process is a self-serve route through MPAC, and you do not need to retain a private tax consultant to begin.

Tax consultants are private entities. They are not connected to your municipality. If you choose to hire assistance, verify the firm, understand the fee structure, ask what services are included, and confirm whether you are paying a percentage of any tax reduction.

Be cautious of unsolicited notices suggesting that your municipality has selected a private company to reduce your assessment. Municipalities do not require you to use a consultant.

A short appeal-preparation checklist

Gold Standard black-and-gold infographic on a dark background showing an appeal preparation checklist for a 2026 Ontario property assessment challenge

  • Confirm your deadline.
  • Request your property details.
  • Pull comparable properties.
  • Photograph anything removed or changed.
  • Locate permits and surveys.
  • Decide whether to file yourself or with help.
  • Diarise the 90-day ARB window in case the RfR decision goes against you.

What this means for cottage and rural owners

For rural and waterfront properties in Muskoka and Parry Sound, the assessment record may include more than the main dwelling.

Shoreline, acreage, outbuildings, boathouses, docks, garages, and accessory structures can all affect classification and assessment, so rural and waterfront owners should confirm that the structures on their record are accurate and that anything demolished or removed is no longer reflected.

An assessment notice does not establish shoreline ownership. Review title, surveys, easements, and applicable agreements separately.

The takeaway

A frozen assessment does not mean a fixed tax bill, and a wrong assessment is worth challenging because the correction carries forward. The self-serve route exists, and the deadlines are real.

AP Bains, REALTOR®, can help you with current market valuation and broader property decisions as you plan your next move.

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AP Bains, REALTOR®
AP Bains | CENTURY 21 Green Realty Inc. Brokerage
416-817-8110
info@apbains.com
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This article is general information only. Assessment appeals, tax questions, and legal questions should be directed to MPAC, Tribunals Ontario, your municipality, a qualified tax professional, or a licensed lawyer, as appropriate.