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Spousal Trust vs Alter Ego Trust: Key Differences in Ontario

Compare a spousal trust and an alter ego trust in Ontario: who can use each, how tax works on death, and what to ask about probate before you decide.

Family Law4 min readTSLBy the Treadstone Law Team · OntarioUpdated November 6, 2026
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Key takeaways
  • A qualifying spousal trust must be created by the deceased's will, and the surviving spouse must be entitled to all of its income during their life.
  • A spousal trust that meets the conditions can defer capital gains tax until the surviving spouse dies, while one that fails them loses the rollover.
  • Probate and alter ego trust rules depend on the trust's terms and your facts, so confirm them with a lawyer and an accountant before you sign anything.

If you are an older Ontarian planning for a partner, you may have heard of both spousal trusts and alter ego trusts. They sound alike, but they are different tools built for different goals, and they are taxed differently.

This article explains what is clearly set out for the spousal trust, then shows which questions to ask about an alter ego trust and about probate. Trust planning is detailed, so the final choice is best made with a lawyer and an accountant.

What a spousal trust is and who can use one

A spousal trust holds property for a surviving spouse or common-law partner instead of handing it over outright. It is often used when the person leaving the property wants to control where it goes after the survivor dies.

For the tax rollover, a qualifying spousal trust must be created by the deceased's will. The surviving spouse must be entitled to all the trust income that arises before their death, and no one else may receive or use trust income or capital during the spouse's lifetime.

The rollover is not limited to married couples. It applies to a surviving spouse or common-law partner resident in Canada, or to a testamentary spousal trust.

How a spousal trust is taxed on death

The starting rule is that a person is treated as having sold their capital property at fair market value immediately before death. That can create a large capital gain on the final return.

The spousal rollover is the exception. If capital property passes to a surviving spouse or common-law partner resident in Canada, or to a testamentary spousal trust, the deceased is treated as selling at adjusted cost base, so the capital gain on the final return is zero. The survivor or trust takes over the deceased's cost.

A trust that does not meet the conditions does not get the rollover. The cure under s. 70(7) is available only where the problem is testamentary debts. Careful drafting matters.

Where an alter ego trust fits

An alter ego trust is a different planning tool from a spousal trust, and it is worth understanding how the two differ before you compare them.

Comparing the two is easier once you know how each one is created and taxed. The eligibility requirements and the tax treatment on death for an alter ego trust depend on how it is drafted and on your age and circumstances. Ask a lawyer and an accountant to confirm them in writing before you transfer any property. Do not assume it follows the spousal trust rules above.

Probate, the will and a spouse's election

Probate tax is one of the main reasons people compare these trusts. Whether a trust reduces it depends on what property goes into the trust and how it is set up, so ask for a written estimate for your own estate.

A trust in a will also has to coexist with a married survivor's rights. A surviving spouse can claim half the difference in net family property under the Family Law Act, take what the will gives, or, with no will, take their share under the Succession Law Reform Act. The election form must be filed with the Estate Registrar for Ontario within six months of the death.

If the survivor elects equalization, gifts to them in the will are deemed revoked unless the will expressly says the gifts are in addition. That can undo the plan a spousal trust was meant to carry out, so the will wording matters.

What to do next

Frequently asked questions

Can a spousal trust be created outside a will?

For the tax rollover discussed here, a qualifying spousal trust must be created by the deceased's will. If you are thinking about a trust set up during life, ask a lawyer and accountant how it would be treated.

Does a spousal trust avoid tax completely?

No, it defers it. The gain is taxed when the trust is treated as selling its capital property at the end of the day the beneficiary spouse dies.

Does a common-law partner qualify for the spousal rollover?

Yes. The rollover applies to a surviving spouse or common-law partner resident in Canada, or to a testamentary spousal trust.

Will a trust reduce probate tax?

It depends on what is placed in the trust and how it is structured. Ask a lawyer for an estimate based on your actual property.

Sources

Links go to official government, court and regulator pages. The law changes — confirm you are reading the current version.

This article is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws, tax rates, and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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