Before you start

Social Insurance Number
T4 slips from employers
Records of foreign income and foreign property
A determination of the date you became a tax resident

Step-by-step

1
Establish the date you became a tax resident
Canadian tax residency turns on residential ties — a home, a spouse, dependants, then secondary ties such as bank accounts and a driving licence — rather than on a day count. Your first return covers only the part of the year after that date.
OnlineWho: You
2
File one return by 30 April, covering both governments
Ontario tax is calculated on the federal return and collected by the CRA. Certified software is free for most situations and free volunteer clinics exist for modest incomes, which many newcomers qualify for in their first year. File even for a short part-year, because the assessed return is what triggers the GST/HST credit, the Canada Child Benefit and the Ontario Trillium Benefit.
OnlineWho: YouBy 30 April
3
If you buy, budget the provincial land transfer tax only
Ontario charges land transfer tax on a purchase. Toronto charges a second, municipal one of similar size on top; London does not, and neither do most Ontario municipalities. On a median London house that difference is thousands of dollars, and it is one of the few genuine tax gaps between Ontario cities. First-time buyers can claim a provincial refund up to a set maximum.
OnlineWho: You
4
Set up the property tax instalments if you own
The City bills interim taxes in late February and late March and final taxes at the end of June, August and October, calculated from your MPAC assessment plus the education portion the province sets. Pre-authorised payment spreads it; missing an instalment attracts interest immediately.
OnlineWho: YouFive instalments a year
5
Report foreign property above the threshold on form T1135
Residents holding specified foreign property costing more than CAD 100,000 in total must file this each year. Penalties for non-filing are severe and applied per year, and a property you still own abroad is the usual trigger.
OnlineWho: You
6
Register for CRA My Account once you have filed
This is where tax slips, benefit payments and refunds live. Registration requires information from a filed return, so most newcomers complete it after the first filing rather than before.
OnlineWho: You

Documents you’ll need

Social Insurance Number
T4 and other information slips
Records of foreign income, accounts and property
Property tax bill and MPAC assessment notice, if you own
Receipts for medical expenses, childcare, tuition and rent paid (for the Ontario Trillium Benefit)

Things most newcomers don’t know

Renters can claim the Ontario Trillium Benefit, and newcomers routinely leave it on the table.

The Ontario Energy and Property Tax Credit inside the Trillium Benefit is available to tenants as well as owners, based on rent paid for a principal residence in Ontario during the year. It is claimed on the annual return and paid monthly. People who assume 'property tax credit' means owners skip the section entirely, and the amounts over a year are not trivial for someone on a modest income. Keep a record of rent paid and the landlord's name.

Source: CRA — Ontario Trillium Benefit

London charges no municipal land transfer tax and no vacant unit tax, and both matter more than they sound.

Toronto levies a municipal land transfer tax that roughly doubles the closing cost of a purchase; Toronto, Ottawa and Hamilton all run vacant unit taxes with a compulsory annual declaration, where simply failing to file is treated as a vacancy and taxed. London has neither. If you are moving from one of those cities you can drop two recurring administrative obligations and one large one-off cost — but do not assume the reverse when comparing back, because the headline property tax rate here is higher than Toronto's, as it is in most Ontario cities outside the GTA.

Source: City of London — property taxes; Ontario land transfer tax

There is no Ontario city with an income tax advantage, and people keep hunting for one.

Income tax is federal plus provincial and identical across Ontario; HST is 13% province-wide. The only municipal levers are property tax and, in Toronto alone, a municipal land transfer tax. London's genuine financial advantage over Toronto is the price of housing and the price of car insurance, and both are substantial — but neither is a tax advantage and treating them as one leads to bad comparisons.

Source: Canada Revenue Agency — Ontario tax rates

File a part-year return even if you earned almost nothing.

The assessed return is what starts the benefit machinery — the GST/HST credit, the Canada Child Benefit, the Ontario Trillium Benefit. Newcomers who arrive in October reasonably conclude there is no point filing for three months of income, and then wonder for a year why no benefit payments arrive. The return is the trigger, not the income.

Source: CRA — Newcomers to Canada

Common mistakes to avoid

Skipping the first part-year return and forfeiting the benefit entitlements it triggers.
Missing the Ontario Trillium Benefit as a renter because the credit's name mentions property tax.
Assuming a 183-day rule determines when you became a tax resident.
Comparing London's property tax rate to Toronto's without noticing Toronto's extra land transfer tax.
Missing a property tax instalment — interest applies immediately.
Missing form T1135 on foreign property costing more than CAD 100,000.
Expecting an Ontario municipality to offer an income tax advantage. None does.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.