Property Assessment Change Notices: renovations, new homes and supplementary tax bills

Why you receive a change notice

A Property Assessment Change Notice (PACN) is not a tax bill. MPAC says it sends these notices "each month between April and November" when a property changes. The reasons it lists:

• an addition, new construction or a renovation;
• a structure assessed for the first time, such as a pool or a garage;
• a change in classification, such as a new structure used to run a business;
• a property that no longer qualifies for the farm, conservation land or managed forest programs;
• a property that no longer qualifies as tax exempt.

How MPAC finds out

Usually through the building permit. MPAC writes: "If you update your property after getting a building permit, your municipality will notify MPAC." It may then call or inspect, updates the value and mails you the PACN.

For a newly built home, MPAC says it assesses the property "within one year of occupancy." The value is still as of January 1, 2016, for the home in its current state, as if it already existed on that date. In November, you also receive a summary Property Assessment Notice showing the value of the whole property.

Supplementary or omitted: the difference

A change notice rests on section 33 or 34 of the Assessment Act. MPAC's sample PACN says so outright: "This assessment is made under section 33 or section 34 of the Assessment Act."

A supplementary assessment (s. 34) covers an increase in value during the year, after notices went out, when a building that was erected, altered or enlarged "commences to be used." It also covers a lost exemption or a change in class.

An omitted assessment (s. 33) covers land or a building left off the roll "for the current year or for all or part of either or both of the last two preceding years," with no taxes levied. The municipality then collects the taxes that would have been payable.

MPAC applies a threshold: it only issues a supplementary or omitted assessment if the value rises by 5% of the current assessment, or by $10,000 or more. Otherwise, the increase is added to the roll for the following tax year.

How the supplementary tax is calculated

The Act sets the rule for a supplementary assessment: the tax is what would have been levied "for the portion of the taxation year left remaining after the change occurred" (s. 34 (1)). MPAC explains it this way: supplementary assessment × tax rate, prorated by the number of days the building has been complete or occupied.

The City of Toronto describes its billing. Supplementary and omitted bills are issued separately from the regular billing cycle, throughout the year. They are due in two instalments "regardless, of the number of years for which you are billed," and cannot be paid through the Pre-Authorized Tax Payment program. For a new home, the City warns that the first regular bill may cover only the land, and suggests estimating the coming bill with the purchase price multiplied by the year's tax rate. Each municipality has its own schedule: check yours.

Challenging it within 120 days

After a change notice, you must file a Request for Reconsideration within 120 days of the Issue Date printed on the notice (Assessment Act, s. 39.1 (3)). In MPAC's sample, a PACN issued on April 6, 2026 carries an August 4, 2026 deadline. Your own deadline is printed on your notice.

According to the sample PACN, you can dispute the effective date of the change, the assessed value or the classification. For a residential property, the reconsideration is free and required before an appeal. For other classes, a direct appeal to the Assessment Review Board is possible within the same 120 days (s. 40 (8)).

Two precautions. First, pay the bill as issued: Toronto states "You must pay your supplementary and/or omitted property tax bills as issued," or face penalty and interest; the Act provides for a refund of any overpayment if the assessment goes down (s. 39 (6)). Second, if your tenants reimburse taxes under their lease, give them a copy of the notice within 14 days (s. 35 (2)).

Other notices MPAC may send

An Amended Property Assessment Notice revises an earlier notice or fixes a factual error in the value, classification or tax liability. The 120-day deadline also applies to it (ss. 35 (1) and 39.1 (3)). To spot a factual error, see the checklist. For evidence of value, see evidence that works, and for the whole process, the complete guide.

Frequently asked questions