Supplementary tax bill

If you’ve made additions or improvements to your home or business property, the assessment value of your property might change.

The Municipal Property Assessment Corporation (MPAC) determines if the property assessment value must change.

If the value is changed, MPAC will send you a Property Assessment Change Notice by mail and the City will send you a supplementary tax bill that reflects this change.

Why a supplementary tax bill is issued

The City will issue a supplementary tax bill if MPAC has made a property assessment change. For example:

• Your house was recently built and at the time of purchase, you only paid the taxes for the vacant land’s value
• A new building was constructed on your property
• You made renovations or external improvements such as an extension, pool or separate building that increased its market value
• Your property’s tax class changed due to the changed use of all or part of the property

When a supplementary tax bill is issued

The City issues a supplementary tax bill only after MPAC provides the property assessment value information for any new construction or use changes.

Supplementary taxes are prorated in the first year, meaning they’re adjusted or calculated based on the effective date of the supplementary assessment value as received from MPAC.

• For example, for newly constructed, detached, semi-detached and terraced houses, the effective date is the closing date. For condominiums, the effective date is the date you can occupy the unit (not the date you receive legal title).

Supplementary taxes apply to all relevant years that MPAC assesses (limited to the current and two previous years as applicable).

How supplementary taxes are calculated

Supplementary taxes are calculated using the applicable tax rate for the year being assessed and supplementary assessment value, then prorated for the number of days from the effective date.

Pay supplementary taxes

Supplementary taxes are due in three instalments.

If you’re enrolled in the Pre-Authorized Tax Payment (PTP) plan, payments will be withdrawn from your bank account automatically. If you’re not enrolled in a PTP plan, check out payment options you can choose.

Dispute a supplementary assessment

If you think your supplementary property assessment is incorrect, you can:

• Submit a Request for Reconsideration (RfR) to MPAC (required for residential properties)
• Appeal to the Assessment Review Board (ARB) within 90 days of the date of the Property Assessment Change Notice from MPAC (residential properties must request an RfR before appealing to the ARB)

The City does not assess property values. All disputes must be made to MPAC or the ARB.

Contact us

For questions about supplementary tax calculation or payment methods, call 311 (905-615-4311 from outside City limits) or email tax@mississauga.ca.

For questions about the supplementary assessment value, please contact MPAC.