"It all depends on how your assessment changed relative to every other property within the area. If you are similar to the average there should be no impact as a result of the reassessment," he said.

Townhouses and semi-detached homes had the highest average annual assessed increases at 9.5 per cent and 9.6 per cent respectively. The typical townhouse or row house in Toronto is valued at $666,000; a semi at $653,000.

The highest residential assessments in Toronto — 12 per cent annually on average — are in the wards of Davenport, Scarborough-Rouge River and Scarborough Centre.

But in Willowdale, Trinity-Spadina and Toronto Centre-Rosedale, overall annual residential assessments were lowest, rising only 2 to 2.5 per cent on average. That's because their assessments were higher relative to other areas of the city in 2012.

Condos are also a factor. Although some of the most expensive real estate in Toronto is downtown, some of the lowest valuations are in the core because the residential landscape is dominated by lower-valued condos rather than single-family homes.

The assessment also depends on what properties sold in a given time frame, said Martino. 

"When we're quoting our numbers, we're talking about the entire population, whether it be single-family, detached, condominiums — the whole gamut. If you've got a month where you've got a lot of high-end, single-family detached selling it could be driving up average value,” he said. “This gives you a view of the entire population."

This year's valuations are based on the property's assessed value of Jan. 1, 2016.

"The key question a property owner should ask themselves is, 'If I were to sell my house on Jan. 1, 2016 is this assessed value something that I think I could have reasonably achieved?' If they can answer that question, 'yes,’ then that assessment is accurate," said Martino.

If not, the homeowner can call MPAC or do some research themselves at its website,aboutmyproperty.ca.

A first round of Toronto assessments will be mailed on Friday with the remainder going out on June 1 and 6.

The Toronto increases compare with a Mississauga annual average of 6.8 per cent and Brampton and Barrie averages of 6.6 per cent each. Those assessment notices have already been mailed.

Other 905-area assessments will go out mid- to late June. Preliminary MPAC data shows they range from 7 per cent in Milton and Oakville to 12 per cent in Whitchurch-Stouffville and Richmond Hill.

Top 3 average assessed neighbourhoods:

Davenport

Average increase since 2012:

11% overall residential

12% single family homes – typical residential home assessed at $839,000

3% condominiums – typical condo assessed at $320,000

Scarborough-Rouge River

Average increase since 2012:

11% overall residential

12% single family homes – typical residential home assessed at $740,000

5% condominiums – typical condo assessed at $268,000

Scarborough Centre

Average increase since 2012:

11% overall residential

11% single family homes – typical residential home assessed at $576,000

4% condominiums – typical condo assessed at $211,000

Lowest 3 average assessed neighbourhoods

Willowdale

Average increase since 2012:

2% overall residential

1% Single family homes – typical residential home assessed at $1.19 million

1% condominiums – typical condo assessed at $398,000

Trinity-Spadina

Average increase since 2012:

2% overall residential

10% single family home – typical residential home assessed at $1.38 million

2% condos – typical condo assessed at $412,000

Toronto Centre – Rosedale

Average increase since 2012:

2.5% overall residential

10% single family home – typical residential home assessed at $1.2 million

2% condos – typical condo assessed at $424,000

Average for communities around GTA:

•Barrie 6.6%

•Mississauga 6.8%

•Brampton 6.6%

Do-it-yourself assessments

MPAC's website lets property owners compare their assessment to up to 100 other homes.

A redesigned MPAC website will allow owners to get a complete look on the information behind their property valuation and compare their home with up to 100 others in their neighbourhood.

To access the information, homeowners need to type in the roll number and access key clearly listed on their assessment notice.

That enables them to download a complete report with all the information the Municipal Property Assessment Corp. has on file about their home.

"The privacy commission has reviewed and awarded the site," said MPAC chief operating officer Rose McLean.

Those who want their assessment reconsidered by the Municipal Property Assessment Corp. can look at other homes in their neighbourhood to figure out how their own stacks up.

The new website allows users to build a list of "favourites" as they search so they can go back and exam those properties more closely.