The deed decides, and birthdays do not change it
Nothing in trust law or tax law removes a beneficiary for turning 18, 25 or 40. Read your deed's definition of beneficiaries: the standard drafting names your children as a class, often adding their spouses, your grandchildren and a corporate beneficiary, and that class membership continues for the life of the trust unless the deed itself says otherwise. If your children were beneficiaries at 12, they are beneficiaries at 22, with no amendment, election or filing required.
The check worth doing is the opposite one: confirming who else the deed quietly includes or excludes. Some deeds capture children's spouses, which families sometimes regret; some exclude non-residents; some give trustees a power to add or remove beneficiaries. Adding someone who is not already inside the defined class is a legal amendment with potential tax consequences, so it goes through the lawyer who drafted the deed, not through wishful reading. Where the class already covers your adult kids, which is the usual case, there is nothing to fix.
So take the yes and move to the better question. A trust full of minors is mostly a waiting room, because tax rules make paying income to minors pointless. A trust full of adults is a working structure with real choices, and the rest of this page is about those choices.
What turning 18 actually changes for tax
Adulthood upgrades a beneficiary from automatic top-rate treatment to conditional own-rate treatment. While your children were minors, any private-company dividends allocated to them were taxed at the top marginal rate, full stop, under rules that have policed income to minors for decades. Once they are adults, the tax-on-split-income rules still apply by default, but exclusions become available, and the exclusions are where planning lives.
The exclusion that matters most through a trust is genuine work: an adult child engaged in the business on a regular, continuous and substantial basis, with an average of 20 hours a week as the working benchmark, in the current year or any five earlier years, can be allocated dividends taxed at their own graduated rates. Note the five-year memory: a child who worked through five university summers and weekends can bank the exclusion for later years. The five years do not need to be consecutive, which rewards families who track hours properly from the start.
Two more doors open with age. Capital gains that qualify for the lifetime capital gains exemption are outside the split-income rules entirely, so on a sale of the business the trust can allocate gains to adult children and each can shelter up to $1.25 million with their own exemption, active in the business or not. And from age 25, an excluded-shares test exists for family members who hold 10 per cent of votes and value directly, but shares sitting in the trust do not count for it; using that door means distributing shares out to the child first, a real step with real consequences, not a checkbox.
Attribution risk, the other rule parents worry about, largely retires at adulthood. The rules attributing investment income back to a parent apply to minor children and to spouses, not to adult children, though the corporate version tied to freezes has its own conditions worth checking annually. The full who-pays map, including these rules, is laid out in how family trusts are taxed in Canada.
What adulthood means for the trust's endgame
Adult children are not just permitted beneficiaries; they are the exit. Every family trust faces a deemed disposition of its property at fair market value on its 21st anniversary, and the standard defence is rolling the shares out to beneficiaries at cost before that date. That rollout is only available to Canadian-resident beneficiaries, and as a practical matter it lands on the adult children, because they are who the structure was built for. A trust with adults in it can stage that handover deliberately over years instead of scrambling at the deadline.
Adulthood also activates their legal position. Adult beneficiaries of a discretionary trust do not have a right to be paid, but they are owed the trustees' honest exercise of discretion and can, in the right circumstances, compel an accounting of what the trust has done. In a harmonious family this is invisible; in a strained one, it is leverage. Trustees who keep proper resolutions and records have nothing to manage here, which is one more argument for the discipline described in what records trustees have to maintain.
Here is the before-and-after in one view:
| Question | While the child is a minor | Once the child is an adult |
|---|---|---|
| Still a beneficiary? | Yes, per the deed | Yes, unchanged |
| Dividends at their own rate? | Never | Yes, if a split-income exclusion applies, chiefly real work in the business |
| Exemption-eligible gains on a sale? | Possible but rarely practical | Yes, their own exemption of up to $1.25M each |
| Attribution back to the parent? | A live concern | Largely retired, outside the corporate freeze rules |
| Can receive the 21-year share rollout? | Technically, but rarely wise | Yes, if Canadian-resident; this is the standard exit |
The risks adult children bring with them
The honest trade-off is that adults come with adult lives attached. A discretionary interest is well insulated from a child's creditors and, to a meaningful degree, from a marriage breakdown, but the insulation weakens the moment shares or cash are actually distributed to them: distributed property is simply theirs, exposed to their divorce, their business risks and their spending. Trustees weighing the 21-year rollout are also weighing which child can safely hold wealth outright, and a shareholders' agreement among the children belongs in that conversation.
Residence is the quiet complication. A child who moves abroad cannot receive the tax-deferred rollout, and allocations to non-residents carry their own withholding and reporting mechanics. If one of your adult children is eyeing a job in another country, that fact belongs in the trust plan now, not at year 20. Family conflict is the loud complication: adults can disagree with trustees in ways minors cannot, and a deed that names how trustee decisions are made and succeeded is worth more than any amount of goodwill.
The facts that change the answer, and what we would check
Whether your adult kids should remain beneficiaries, as opposed to merely can, turns on a handful of facts. Whether any of them genuinely works in the business, with hours you could evidence, because that decides whether the trust can pay them at their own rates. Whether a sale of the company is plausible, because exemption multiplication across adult children is the structure's biggest remaining prize. Where each child lives or plans to live. How old the trust is, because proximity to the 21-year mark reframes everything. And the state of their marriages and finances, because the rollout ends the trust's protection.
What we actually do on these files is unglamorous: read the deed, confirm the beneficiary class, map each adult child against the split-income exclusions, and put a date on the 21-year anniversary with a staging plan for the years before it. That review is a defined-scope piece of work under Strategic Projects, often the first thing a business estate planning CPA in Ontario does on a trust file, and it starts with a free 15-minute call. If you are earlier in the journey and the trust does not exist yet, start with whether a family trust would do anything for you before worrying about who is in it.
