A4 Form Explained: Changing a Tax-Driven Rent Reduction in Ontario, Step by Step

Ontario's A4 form lets someone ask the Landlord and Tenant Board (LTB) for a different number. When a building's property taxes go down far enough, its rents go down with them, automatically, by a percentage the municipality works out. The A4 is how you argue that percentage doesn't fit. Landlords file most often; tenants can too.

Quick summary

What this application actually changes

The automatic part. Under s. 131 of Ontario's Residential Tenancies Act, 2006 (the RTA), a drop of more than 2.49% in a residential complex's municipal property tax pulls every unit's lawful rent down as well. No one applies; it simply happens, with December 31 of the tax-reduction year as the effective date (O. Reg. 516/06, s. 41).

The formula. Percentage tax drop × 20% if the property sits in the multi-residential class; × 15% for everything else.

The notices. Where the complex has seven or more units, the municipality mails a Notice of Rent Reduction: the landlord gets theirs some time from June 1 to September 15, the tenants theirs from October 1 to December 15.

Where the A4 fits. RTA s. 132, along with s. 42 of the regulation, allows a challenge to that percentage on four grounds. Those grounds are exactly the four reasons you'll see on the form. If the Board is persuaded, it issues an order fixing the percentage.

What it can do for you:

• Landlord: argue the cut is bigger than the building's true numbers support.
• Tenant: point out that a notice got the figures wrong, or that taxes shifted afterward.

Who can't use it. If your unit falls under the s. 6.1 exemption from the rent rules (buildings, additions or certain second units first occupied as homes after November 15, 2018), s. 132 doesn't apply, so neither does the A4.

Do you need an A4? Check these first

Tick every one that applies.

• [ ] Reason 1 — charges were missed. During the base year the municipality billed amounts beyond the tax itself and they weren't counted. Things like a garbage user fee or a special levy qualify. Things that don't qualify: inspection charges, repair charges for emergencies or by-law orders, capital-work charges, vital-service costs, and any penalty, interest or fine.
• [ ] Reason 2 — the ratio is wrong for this building. The formula pretends taxes equal 20% (multi-residential) or 15% (other) of a year's rent. If yours don't, the Board can redo the math with the rent the complex really brings in. Landlords whose tax bill is a modest share of their rent roll tend to come out ahead.
• [ ] Reason 3 — the notice has a mistake in either the tax decrease or the rent reduction it shows.
• [ ] Reason 4 — base-year taxes later went up or down, for example because of a reassessment or a successful appeal, and the change came before March 31 in the year following the one when the reduction kicked in.

Pick a different form if:

• you're a tenant wanting your own reduction under s. 133 because municipal taxes and charges went down — that's the T3, the tenant's Rent Reduction application;
• you're a landlord facing higher taxes and want an above-guideline increase — that's the L5.

Counting the days

Your last day is the later of:

• A. 90 days after the Notice of Rent Reduction reached you. (Building under seven units, so no notice was required? Then start counting on the day the tax notice that created the decrease was issued.)
• B. March 31 in the calendar year following the year the rent reduction takes effect (O. Reg. 516/06, s. 42(2)).

An example with real dates. Taxes on a 14-unit walk-up in Kingston fell in 2027, so the cut takes effect Friday, December 31, 2027.

Watch the wording. The form and the instructions talk about the date the municipality issued its notice; the regulation talks about when you were given it. Count from the earlier one.

No extensions. The regulation sets this limit. The Board can't stretch a prescribed time requirement, and RTA s. 190 doesn't list s. 132 among the applications whose filing time it may extend.

Mailing it? Rule 4.8 deems a mailed document filed on the fifth day after mailing that isn't a holiday, and Rule 1.1 counts Saturdays and Sundays as holidays. Mail it Friday, March 24, 2028: Monday the 27th is day 1, and day 5 lands on Friday, March 31 — the very last day.

If the Board orders service (Rule 5.2):

1. Written hearing → serve no more than 20 days after the Board's notice goes out (Rule 5.6).
2. Oral hearing → serve no fewer than 30 days ahead of the hearing (Rule 5.7).
3. Then, within five days of serving, file your Certificate of Service (Rule 5.15).

Filling in the form, one part at a time

The form in use is version 01/04/2022. Type it or print in block capitals. Parts 1, 2, 3 and 5 are for everyone; add Part 4 when you rely on Reason 2 or want rent revenue weighed. See the official A4 instructions.

Part 1 — General Information

1. Applicant Information. Landlords shade "Landlord" and add a name (or company name), mailing address, phone numbers and email.
2. Address of the Rental Unit, Building or Residential Complex. Every building the application reaches, by street address. Not enough room? Attach a page.
3. Other Parties to the Application. A landlord shades "Tenant." For a building-wide case, one tenant goes on the form itself; everyone else, unit by unit, goes on a Schedule of Parties.
4. Notice of Rent Reduction. Received one from the municipality? It must go in with the form.
5. Related Applications. Any open file numbers.

Part 2 — Information about Municipal Property Taxes

You'll name two years:

• Base year — the calendar year in which taxes fell and the rent reduction takes effect.
• Reference year — the calendar year immediately before.

For each, enter the complex's total property taxes. Property tax and education tax only — special levies, user fees and penalties stay out. Attach the bills (or other proof) for both.

Part 3 — Reasons for Your Application

Shade your reasons, then give what each one needs:

• Reason 1: other-charge totals for both years, plus proof.
• Reason 2: say whether the complex is in the multi-residential tax class, then go to Part 4.
• Reason 3: name the error, explain why it's wrong, state the percentage you believe is correct and show your working.
• Reason 4: proof of the change to base-year taxes — a reassessment, an appeal decision or similar.

Part 4 — Information about Rent Revenue

Total annual rent revenue of the complex in the base year. If you ticked Reason 2, this box is required; the instructions are clear that the Board can't consider the application without it. Be ready to back up the rents with evidence (O. Reg. 516/06, s. 44).

Part 5 — Signature

Shade the right box (applicant or "Representative"), then sign and date. Representatives include their Law Society number and how to reach them.

Getting it to the Board

Option 1 — email. Pay online with a Visa or Mastercard (credit or debit). Then, inside 24 hours, send the form, the notice, the evidence and your receipt to LTBpayments@ontario.ca; the subject line should carry the receipt number and the property address.

Option 2 — mail or courier. Enclose a certified cheque or money order payable to the "Minister of Finance", or pay by card on the Credit Card Payment Form.

Option 3 — in person. Any ServiceOntario centre that handles LTB filings.

Fees: $201 for landlords, $53 for tenants, and no refunds (LTB fees page). Can't afford it? Ask for a Fee Waiver Request.

Errors that sink an A4

1. Late filing. A regulation fixes the deadline and the Board cannot extend it, so late means lost.
2. Reason 2 ticked, Part 4 blank. No base-year rent revenue means no recalculation is possible — that ground can't be considered at all.
3. Missing proof. Section 44 of the regulation wants tax evidence for both years, proof of the extra charges (Reason 1), proof of the rents (Reason 2), and a copy of the notice if there was one.
4. Slipping in excluded charges. Section 41(2) rules out penalties, interest, inspection and repair charges, capital-work charges and vital-service costs. Including them taints every figure.
5. Leaving tenants off. Everything the Board does, and any service it orders, runs off your Schedule of Parties. An unlisted, unserved tenant never got notice — and when service fails, Rule 5.17 lets the Board adjourn or dismiss.
6. Charging the old rent in the meantime. The reduction applies by law whether or not a notice was ever sent (s. 131(2)). Collecting the pre-reduction rent before any variation order invites tenant applications over money collected illegally.

What to expect next

• Hearing. An A4 can be decided on paper (Rule 5.6 provides for written hearings). Got a notice of written hearing? Serve it inside 20 days. Otherwise you'll attend an oral hearing.
• The order. It sets the percentage, effective back to the date fixed by s. 131 (see s. 132(4)).
• Afterwards. Adjust rents; refund or credit overpayments.
• If you disagree. For an order dated July 1, 2026 or later, there are 15 days to ask for a review (Rule 26.5) — see Request to Review an Order.

Questions people ask

At what point does a tax decrease lower the rent?

Only past 2.49%. Once the drop in the complex's municipal property tax is larger than that, the rent goes down by itself, and the effective date is December 31 of the year the lower tax takes effect.

How is the percentage worked out?

Take the tax decrease as a percentage. Multiply by 20% (multi-residential class) or 15% (any other class). A Reason 2 application replaces that assumption with the complex's real rent revenue.

I own a fourplex. Should I expect a notice?

Municipalities are only obliged to send them for complexes of seven or more units. Your rents are still reduced, though, and your A4 deadline counts from the tax notice instead.

As a tenant, am I allowed to file?

Yes — tenants affected by the reduction can apply, and their fee is $53.

Official sources

• Form A4 – Application to Vary the Amount of a Rent Reduction (PDF)
• A4 Instructions
• LTB Forms, filing and fees
• Residential Tenancies Act, 2006, ss. 131–132
• O. Reg. 516/06 (General), ss. 41–44
• LTB Rules of Procedure

Last reviewed October 31, 2026. General information, not legal advice for your situation. Always use the current version of the form from the LTB.