# Will an addition or ADU raise my property tax in Hamilton?

> How an addition, ADU or major renovation can change a Hamilton home's MPAC assessment and property tax: the change notice, the 2016 value date, reconsideration.

- Canonical HTML: https://www.jdtconstruction.ca/guides/property-tax/
- Section: Home > Guides > Property tax after a build
- Business: JDT Construction Inc., Hamilton, ON, Canada (serves Hamilton)
- Phone: (905) 818-0106 | Email: johnny@jdtconstruction.ca
- Page updated: 2026-11-05

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Guides

It can. When a Hamilton home gets an addition, a new building such as a garden suite, or a major renovation, MPAC, which assesses Ontario property for tax, updates the assessment and mails a Property Assessment Change Notice. The value is still set as of January 1, 2016, but in the home's current state, so the added space counts. JDT Construction cannot say by how much: MPAC sets that.

## When does MPAC reassess?

When the property changes. MPAC: “When there is a change in a property (such as new construction or major renovation), MPAC updates the assessment and mails a Notice.” It sends a Property Assessment Change Notice when “There was a change to your property such as an addition, new construction or renovation”, when it assesses a structure for the first time, or when the classification changes [(MPAC, Notices and Notifications, read November 5, 2026)](https://www.mpac.ca/en/UnderstandingYourAssessment/NoticesandNotifications).

## What value does it use?

**How MPAC values a changed home for the 2026 tax year**

| Question | MPAC's answer |
| --- | --- |
| Which date? | January 1, 2016: the province postponed reassessment, so 2016 values still set 2026 taxes |
| Which house? | “in its current state and condition, including any major changes since then” |
| Does MPAC keep reviewing? | “as new homes are built, owners renovate, structures are demolished, and properties change use” |
| How do I see it? | On AboutMyProperty, with the roll number and access key on the notice |
| What if I disagree? | A residential owner files a Request for Reconsideration with MPAC before any appeal to the Assessment Review Board |

All from MPAC [(MPAC, Notices and Notifications, read November 5, 2026)](https://www.mpac.ca/en/UnderstandingYourAssessment/NoticesandNotifications). The 2016 date stays because the Ontario government, in MPAC's words, filed a regulation to amend the Assessment Act extending the postponement of province-wide reassessment [(Assessment Act, R.S.O. 1990, c. A.31, read November 5, 2026)](https://www.ontario.ca/laws/statute/90a31). The tax itself is the assessment times the City's tax rate for the year.

## Which builds are likely to change it?

The ones MPAC names: an [addition](https://www.jdtconstruction.ca/builds/additions/), new construction such as a garden suite, or a major renovation. Smaller work, like new cabinets or replacing windows, is not on MPAC's list.

## Is there a one-time charge too?

A new house pays development charges, and an ADU usually does not: [development charges](https://www.jdtconstruction.ca/guides/development-charges/) has the 2026 to 2027 numbers. The building permit fee is in [what a building permit costs](https://www.jdtconstruction.ca/guides/permit-fees/). JDT Construction Inc.'s written proposal covers the build; the City's and MPAC's charges are separate from it.

Published by JDT Construction Inc., Hamilton. Updated November 5, 2026. Free to share and quote, with a link back to this page.

## Planning a build?

JDT draws it on a picture of your property and prices it in one written proposal.

[Call (905) 818-0106](tel:+19058180106) [Request a quote](https://www.jdtconstruction.ca/request/?problem=addition)

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JDT Construction Inc. Call (905) 818-0106. Full site: https://www.jdtconstruction.ca/