School Tax in Montreal: Calculation, Deadlines, and Payment

If you own property on the island of Montreal, you owe an annual school tax to the Comité de gestion de la taxe scolaire de l’île de Montréal (CGTSIM). For the 2025–2026 year, the Montreal school tax is charged at $0.08423 per $100 of adjusted standardized assessment, with the first $25,000 of value exempt. Bills go out shortly after July 1.¹

Who Owes the Tax

Every owner of a taxable property on the island pays. It does not matter whether you have children, whether they are in school, or which language they study in.²

The school year runs July 1 to June 30, and the person listed as owner on July 1 is responsible for the full annual bill. Co-owners share the obligation but receive a single bill for the property rather than separate ones.³

If your mailing address is different from the property address, update it through the CGTSIM’s online form. Owners with an address outside Canada should put the full address in the message field, and business entities have to use the form rather than calling.⁴

How the Bill Is Calculated

Quebec sets one province-wide school tax rate that applies to every school board and school service centre. The government recalculates the rate each year based on funding needs and the combined assessed value of all taxable property in the province.⁵

The formula: take your property’s adjusted standardized assessment (the municipal evaluation multiplied by a standardizing factor), subtract the $25,000 basic exemption, divide by 100, and multiply by the annual rate. For 2025–2026 that rate is $0.08423.⁶

A worked example. If your adjusted standardized assessment is $500,000, you are taxed on $475,000, producing a bill of roughly $400.

Payment Deadlines

Due dates are printed directly on your bill. For 2025–2026:²

If your bill is under $300, one payment is due August 4, 2025.
If your bill is $300 or more, a first installment is due August 4, 2025 and a second is due October 31, 2025.

The two-installment option applies automatically once the bill hits $300. You do not need to request it. Both amounts and both deadlines appear on the bill, along with a detachable coupon for each installment.

How To Pay

The CGTSIM accepts three payment methods. You cannot pay in person at the CGTSIM offices, and the online tax portal itself does not process payments. Credit cards and pre-authorized debits are not accepted.²

Online banking is the recommended route. Add the CGTSIM as a payee through your bank’s website or app, using the 20-digit reference number printed in the upper-right corner of your bill. Payments take two to five business days to process.

You can also pay at your financial institution’s counter by presenting the detachable coupon to a teller. To pay at an ATM, you first have to register the CGTSIM as a payee through online banking or at the counter, because the coupon cannot be inserted into the machine.

To pay by cheque, make it payable to CGTSIM and mail it with the detachable coupon to P.O. Box 11071, Downtown Station, Montréal, QC H3C 5A9. Do not staple the coupon to the cheque. If you owe two installments you can enclose a post-dated cheque for the second payment in the same envelope. A $25 fee applies to any cheque returned by your bank. Payment is credited on the date the CGTSIM receives the cheque, not the date you mail it, so allow time.⁷

Owners with bank accounts outside Canada are limited to mailing a cheque, since the online bill-payment route requires a Canadian financial institution.

One thing to know: the CGTSIM does not issue an official payment receipt. Your bank transaction record is your proof of payment. Keep it, especially if you plan to claim the school tax as an expense on a rental property.

Viewing Your Account Online

The CGTSIM’s online portal lets you view your current bill, check payment history, and switch to paperless billing. To register, use the 9-character Internet registration number printed at the top of your bill. Each owner has a unique number; co-owners whose name is not listed first on the account can request theirs from CGTSIM customer service.⁷

If you opt into online billing, the CGTSIM emails you around July 2 each year to say your new bill is available. The portal keeps prior years’ bills as well. Payment still runs through your bank.

Buying or Selling During the Year

Because the July 1 owner is on the hook for the full year, adjustments during a sale are handled privately between buyer and seller. The notary overseeing the transaction usually prorates the tax so each party covers their share of the year. The CGTSIM does not reissue or split bills, and the notary is required to hand the original school tax bill to the new owner at the signing of the deed.³

If an overpayment falls out of the transaction, the notary contacts the CGTSIM to say whether the refund should go to the buyer or the seller.

What Late Payment Costs

Missing a deadline gets expensive quickly. For 2025–2026, the CGTSIM charges 8% annual interest on unpaid balances, calculated daily from the due date. A $15 administrative fee is added when the initial payment reminder goes out, and another $15 when the first formal collection letter is sent, typically in April.⁸

These charges stack on top of the unpaid principal. A $400 bill left unpaid for a full year would accrue roughly $32 in interest, plus the administrative fees.

A Note on the Senior Grant

Quebec offers a grant program for eligible seniors, but it applies to municipal tax increases, not to the school tax, and it is administered by Revenu Québec rather than the CGTSIM. To qualify for the 2026 grant you must be 65 or older, a Quebec resident, and the owner (or spouse of a former owner) of the residence for at least 15 consecutive years as of December 31, 2025. The home must be a single-dwelling unit serving as your principal residence, your 2025 household income must be $64,200 or less, and you must have received (or been entitled to receive) a municipal tax bill in your name for 2026. The grant is claimed through your Quebec income tax return.⁹

1
Comité de gestion de la taxe scolaire de l’île de Montréal. About the Comité de gestion de la taxe scolaire de l’île de Montréal
2
Comité de gestion de la taxe scolaire de l’île de Montréal. School Tax Payment
3
Comité de gestion de la taxe scolaire de l’île de Montréal. Service for Notaries, Lawyers and Mortgagees
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Comité de gestion de la taxe scolaire de l’île de Montréal. Change of Mailing Address Request
5
Publications du Québec. Bill 3 – An Act To Amend the Education Act and Other Provisions Regarding School Service Centre School Taxes
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Comité de gestion de la taxe scolaire de l’île de Montréal. Understanding School Tax
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Comité de gestion de la taxe scolaire de l’île de Montréal. Access Your School Tax Account or Sign Up for Online Billing
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Comité de gestion de la taxe scolaire de l’île de Montréal. Collection Services
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Revenu Québec. Grant for Seniors To Offset a Municipal Tax Increase