By A.J. Keilty, President, KEILTY Realty Management
Yes, if the value on your notice is wrong and the saving will stay with you: asking MPAC to take another look is free, and the deadline is March 31 of the tax year you want changed. But in a building that was lived in on or before November 15, 2018, if your tax bill ends up more than 2.49 per cent below last year's, every tenant's rent drops automatically, so run that second number before you file.
You are disputing a value on a fixed past date, not what the house would sell for today. Section 19.2 (5) of the Assessment Act lets the Minister prescribe a different valuation day, and the Minister has. Section 48.6 of O. Reg. 282/98 says "January 1, 2016 is prescribed as the day as of which land is valued for the 2021, 2022, 2023, 2024, 2025, 2026 and 2027 taxation years."
So your evidence has to speak to what the property was worth on the prescribed valuation day, which for every tax year through 2027 is January 1, 2016. A soft market this year does not prove the 2016 figure was wrong. Sales of similar homes around that date, and errors in what MPAC recorded about the building, do.
There is a second argument. Section 44 (3) of the Act tells the Assessment Review Board to determine current value and to "have reference to the value at which similar lands in the vicinity are assessed and adjust the assessment of the land to make it equitable with that of similar lands in the vicinity if such an adjustment would result in a reduction of the assessment of the land."
That instruction binds the Board on appeal. If comparable duplexes on your street are assessed lower, that comparison can carry a reduction on its own.
Start with a Request for Reconsideration to MPAC. Section 39.1 (1) lets "the owner of a property or a person who has received or would be entitled to receive a notice of assessment" ask MPAC to reconsider. Section 39.1 (1.1) sets the deadline: the request "must be made no later than March 31 of the taxation year in respect of which the request is made." For the 2027 tax year that is Wednesday, March 31, 2027.
That deadline applies every year, even with no new notice. The main exception for an owner is section 39.1 (3): after a notice of an omitted or supplementary assessment, for example once you add or finish a unit, you have "120 days after the issuance date on the notice of assessment".
If you miss March 31, section 40 (4) lets the Assessment Review Board extend the deadline for "extenuating circumstances", on an application made "during the taxation year". The ARB's information sheet on extensions says that request is free and goes by email to arb.rfrext@ontario.ca.
The same sheet still gives residential owners "90 days after the mailing date of the notice" to file, which is not what section 39.1 now says, so work from the Act.
Section 39.1 sets no fee for the request; MPAC's Request for Reconsideration page explains how to file. A request can dispute the property's classification as well as its value. Section 39.1 (4) says the request "must set out the basis for the person's request and all relevant facts", so attach your comparables.
MPAC then has a deadline of its own. Under section 39.1 (7), for 2017 and later tax years it must give notice of the result "no later than 180 days after the request is made", or no later than 240 days if it tells you within the 180 days that it needs an extension.
You can appeal to the Assessment Review Board, but only in a set order for a rental house or duplex. Section 40 (3) bars an appeal for property "in the residential, farm or managed forests property class" by a person who did not make the reconsideration request in time. For those properties, the request is not optional; it is the gate.
Section 40 (5) sets the appeal clock. If MPAC issued its decision, the last day is "90 days after the issuance date on the notice provided by the assessment corporation." If MPAC missed its own deadline, section 40 (3.1) still lets you appeal, and the 90 days run from the day the notice should have been provided.
The ARB's filing page describes the 90 days as running "from the mailing date on your RFR decision" and does not mention the late-decision route; the Act's words are "issuance date", so count from that.
An appeal is not free. The ARB fee chart lists $132.50 per roll number for residential, farm or managed forest properties, with a $10 discount when you e-file. It also warns that the ARB sets the fee by property code, not tax classification, so a residential tax class does not settle which fee you pay.
A building of seven or more self-contained units sits outside the residential class, because section 3 (1) of O. Reg. 282/98 limits that class to land "that does not have seven or more self-contained units". For those owners the reconsideration request is optional, section 40 (6) sets a direct appeal deadline of March 31, and the ARB fee is $318.00 per roll number.
One risk is easy to miss. Section 44 (1) lets the Board on any appeal "reopen the whole question of the assessment". An appeal that turns up an unrecorded addition can move the value the wrong way, so check what MPAC has on file first.
The rent goes down with it once the drop clears a threshold. Section 131 (1) of the Residential Tenancies Act, 2006 reads: "If the municipal property tax for a residential complex is reduced by more than the prescribed percentage, the lawful rent for each of the rental units in the complex is reduced in accordance with the prescribed rules."
Section 41 of O. Reg. 516/06 supplies the numbers. The prescribed percentage is 2.49 per cent. The rent cut is the percentage tax reduction multiplied by 20 per cent for a property in the multi-residential property class, "and 15 per cent otherwise". A duplex is in the residential class, so the 15 per cent figure applies.
On a small building, four details decide how this lands:
Rent you keep collecting at the old level after that date is above the lawful rent, and section 111 (1) says "No landlord shall charge rent for a rental unit in an amount that is greater than the lawful rent permitted under this Part." A tenant can claim it back under section 135 without ever receiving a municipal notice, for money collected up to one year before applying (section 135 (4)).
Some newer units are outside sections 131, 132 and 133 entirely. Section 6.1 (2) switches them off for a unit in a building where no part "was occupied for residential purposes on or before November 15, 2018", or entirely in an addition no part of which was.
Section 6.1 (3) does the same for a self-contained unit, with its own kitchen, bathroom and lockable entrance, created after that date in a detached, semi-detached or row house that never held more than two residential units on or before it. The owner must have lived in another unit in the house when the new one was first occupied, or the new unit must have been built in unfinished space, or both.
The exemption has a catch on each side. Section 6.1 (4) says it "does not apply with respect to a rental unit that is subject to a tenancy in respect of which a tenancy agreement was entered into on or before November 15, 2018". Section 6.1 (5) then confines that to the one tenancy, so the exemption revives when that tenant leaves. Under section 6.1 (6) the onus is on the landlord to prove an exemption applies.
Take a hypothetical side-by-side duplex in Oshawa, built decades ago, with both tenants in place since before 2018. Each pays $1,800 a month, so the building brings in $43,200 a year. Last year's municipal property tax was $5,000.
The owner files a Request for Reconsideration by March 31, MPAC agrees the 2016 value was too high, and this year's tax comes in at $4,500. That is a 10 per cent drop, well over the 2.49 per cent threshold. The test is the actual bill against last year's, so a rate increase can absorb a modest win before it ever reaches the threshold.
So $500 saved against $648 given up. The formula assumes taxes are about 15 per cent of rent; here they are about 11.6 per cent, so the automatic cut overshoots. And nothing in section 131 restores the rent if taxes rise again, short of an above-guideline application for an extraordinary tax increase. Every future guideline increase for those two sitting tenants compounds on the lower base.
Yes. Section 132 (1) of the Act lets a landlord or tenant apply "under the prescribed circumstances" to vary the reduction, and section 42 (1) of the regulation lists four circumstances. The one that fits the Oshawa duplex is clause 42 (1) (b): the share of rent that the tax represents "is not 20 per cent" for multi-residential property, "and 15 per cent otherwise".
The other three are extra municipal charges levied in the base year, an error in the notice, and a further tax change between the notice and March 31 of the year after the reduction takes effect.
On that ground, section 43 (3) has the Board take the actual tax decrease, divide it by "the total of the annual rents for all of the rental units in the residential complex", and multiply by 100. In the example that is $500 divided by $43,200, or about 1.16 per cent, which is roughly $20.83 a month per unit. The two totals now match: $500 saved, $500 passed through.
The application is Form A4, Application to Vary the Amount of a Rent Reduction, listed on the LTB forms page with a $201 landlord filing fee and filing by mail or courier, at ServiceOntario, or by email. A tenant can file the same form for $53. Section 44 of the regulation requires evidence of the municipal taxes for both years, and for the clause (b) ground, evidence of the rents charged.
Where no municipal notice is required, as on a duplex, section 42 (2) (b) sets the deadline: the later of two dates. One is 90 days after the tax notice that put the reduction into effect "is issued". The other is March 31 in the year after the year the rent reduction takes effect.
On the Oshawa numbers, $201 to recover $148 a year pays for itself in under two years, but only if you file inside that window.
So with the variation, the whole tax saving goes to the two sitting tenants. The owner keeps the saving only on units that are exempt under section 6.1, and on a unit that turns over, because section 113 makes the lawful rent for a new tenant "the rent first charged to the tenant". This is the opposite of the above-guideline route, where an extraordinary tax increase can lift the rent.
Yes. Section 133 (1) lets a tenant apply for a rent reduction "due to a reduction in the municipal taxes and charges for the residential complex", on Form T3. Section 45 (2) para 1 of the regulation tells the Board that where taxes "are decreased as a result of an appeal of a tax assessment", that decrease is counted.
A settlement at the reconsideration stage is not clearly an "appeal", but an ordinary year-over-year drop is caught by section 45 (3) para 1 anyway.
The bound sits in the same section. Under section 45 (2) para 3 (ii), a decrease from an assessment appeal is not considered if "the application for the rent reduction was filed more than 12 months after the decision on the appeal was issued". Neither section 133 nor the section 45 rules repeat the 2.49 per cent threshold, so a tenant's application is not limited to large drops.
Run the arithmetic per unit before filing. A challenge pays most clearly where the tax saving stays with you: units exempt under section 6.1, units you expect to turn over soon, or a vacant or owner-occupied part of the property. It pays least on an older building full of long-term tenants, where the saving passes through.
Because the March 31 deadline attaches to each tax year, missing it this year does not stop you next year.
A manager's job here is mostly sequencing: pulling the MPAC property record, judging whether the comparables justify a request, diarising March 31 and the 90-day appeal window, and filing the A4 in time when a win triggers an automatic cut. That is the paperwork discipline behind our small multi-family management. For the other side of the same ledger, see the post on covering a higher mortgage payment.
Is there a fee to ask MPAC to reconsider my assessment?
No. The Assessment Act sets no fee for a Request for Reconsideration, so there is none. An appeal to the Assessment Review Board afterwards costs $132.50 per roll number for residential, farm or managed forest property, with a $10 discount for e-filing.
Does a lower property tax bill really reduce my tenants' rent automatically?
Yes, if the tax falls by more than 2.49 per cent and the units are not exempt under section 6.1. Section 131 of the Residential Tenancies Act reduces the lawful rent by 15 per cent of the percentage tax drop, or 20 per cent for multi-residential property, whether or not anyone gives notice.
Can I appeal straight to the Assessment Review Board without asking MPAC first?
Not for a rental house or duplex in the residential property class. Section 40 (3) of the Assessment Act makes a timely Request for Reconsideration a precondition, and the appeal is then due 90 days after the issuance date on MPAC's decision, or 90 days after the date MPAC should have decided if it runs late.
An assessment challenge is one of the few ways to lower a fixed cost, but on a tenanted building the saving rarely stays with you. Check the rent side before you file.
Own a rental in Kingston or Eastern Ontario? KEILTY Realty Management manages it for a flat monthly rate. Get a free rental evaluation or book a 30-minute discovery call with A.J. Keilty.
This post is general information about Ontario property assessment and residential tenancy law as of 2026-11-12, not legal advice. Legislation, regulations and tribunal practice change. For advice on a specific property or situation, speak with a lawyer or licensed paralegal.
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