What Is a Codicil and When Should You Use One in Canada?

A 71-year-old retiree in London, Ontario decides to swap her named executor — her older brother, who recently moved to a long-term care home — for her younger niece. The rest of her will, drafted six years earlier, still reflects her wishes. Her lawyer prepares a one-page codicil naming the niece, has it signed in front of two witnesses, and clips it to the original. Total cost: about $200. The will itself stays untouched, but the executor swap is now legally effective.

That tidy outcome is the case codicils were built for — a narrow, surgical change to an otherwise still-correct will. The trouble starts when people stretch them past that purpose.

What a codicil actually is #

A codicil is a separate testamentary document that modifies, adds to, or revokes part of an existing will without rewriting it. It is treated by Canadian probate courts as part of the same instrument as the original will — the executor presents the will plus every codicil together when applying for probate.

Because the law treats the two documents as one, a codicil must meet the same formal execution requirements as the will it amends.^[1] In each common-law province, that generally means the testator signs the codicil in the presence of two adult witnesses, and the witnesses sign in the presence of the testator and each other. A holograph codicil — entirely handwritten and signed by the testator with no witnesses — is valid in provinces that recognize holograph wills, including Ontario, Alberta, Saskatchewan, Manitoba, New Brunswick, Nova Scotia, Newfoundland and Labrador, and the territories. British Columbia and Prince Edward Island do not.

A common misconception is that codicils are informal — a quick note tucked into the will, perhaps signed but not witnessed. They are not. A codicil that fails the signing formalities is generally just as invalid as a botched will.

When a codicil is the right tool #

The pragmatic test is whether the change is narrow enough that the rest of the will reads unchanged. Three patterns fit that bill cleanly:

Replacing one executor (or guardian, or alternate). The most common reason Canadians prepare a codicil. The named executor has died, become unable to act, moved out of province, or fallen out with the family. Swapping them for the named alternate (or for a brand-new person) is a one-clause change.

Adjusting one specific bequest. Adding a $5,000 gift to a charity. Removing a gift to a friend who has passed away. Changing the named recipient of a particular heirloom. Each of these can be done in two or three sentences without touching the residue clause or anything else.

Updating an address or legal name. If the testator or a key beneficiary has legally changed their name, a codicil can update the will to match. This rarely affects validity — courts ordinarily identify beneficiaries by description rather than exact wording — but a clean update prevents arguments at probate.

The Canadian Bar Association and most provincial law societies generally recommend that codicils be limited to two per will. Beyond that, the document chain becomes unwieldy and the chance of inconsistency rises.

When a codicil is the wrong tool #

Three situations call for a fresh will instead of a codicil:

The residue clause is changing. The residue — who gets "everything else" — is the most consequential clause in any will. Once it is being rewritten, the rest of the document usually needs to be re-examined alongside it, which negates the codicil's value as a surgical instrument.

A new spouse, divorce, or new child is in the picture. Marriage no longer automatically revokes a will in most provinces (Ontario removed the rule in 2022, BC in 2014, Alberta earlier), but life events of this size almost always touch multiple clauses — residue, guardianship, executor, specific gifts. A codicil patched onto a pre-marriage will reads as an afterthought; a fresh will reads as a plan.

The will is more than ten years old. Statutes, case law, and tax rules drift over a decade. A will from 2014 that pre-dates Ontario's substantial-compliance rules, Alberta's reformed Wills and Succession Act timelines, or BC's WESA modernization is often easier to redraft from scratch than to patch.

There is also a practical risk: an inconsistency between the will and the codicil — even a tiny one, such as different spellings of a beneficiary's name — can open the door to a will challenge. Courts work hard to reconcile the two documents, but the safer route is to avoid the inconsistency in the first place.

How a codicil is structured #

A standard Canadian codicil contains five elements, in this order:

The identification clause names the testator and identifies the original will by date and (where applicable) place of execution. "I, [name], confirm that I made my last will and testament dated [date] in [province], and now make this First Codicil to that will."

The amending clauses state, plainly, what is being changed. "I revoke clause 4(b) of my said will and substitute the following..." or "I add the following clause to my said will..." Each amendment is numbered and self-contained.

A confirmation clause affirms that the rest of the will continues in full effect. This matters because, without it, an executor or court has to infer whether the codicil's changes touched the unmentioned clauses indirectly. "In all other respects I confirm my said will."

The signing block mirrors the will: testator's signature, date, and signatures of two witnesses with their addresses and occupations.

An optional affidavit of execution — sworn by one of the witnesses confirming the signing was done properly — speeds up probate later, especially for codicils signed many years before the testator's death.^[1]

Signing requirements by province #

The witnessing rules for codicils mirror the rules for wills, with one or two provincial wrinkles:

Ontario. Two witnesses present at the same time as the testator, both signing in each other's presence. Beneficiaries (and their spouses) under either the will or the codicil should not be used as witnesses — their gift can be void under section 12 of the SLRA, though the codicil itself remains valid.^[1]

British Columbia. Two witnesses present together with the testator (section 37 of WESA). Holograph codicils are not recognized.^[2]

Alberta. Two witnesses, both present with the testator. Holograph codicils are valid if entirely in the testator's handwriting and signed.^[3]

Manitoba. Two witnesses, both present with the testator. Holograph codicils valid.^[4]

Other common-law provinces (SK, NS, NB, NL, PE). Two witnesses, both present with the testator. Holograph codicils recognized in each except PE.

Across the country, every province has now adopted some form of substantial compliance safety net — Ontario joined the list on January 1, 2022 with section 21.1 of the SLRA^[5] — so a botched codicil can sometimes be saved by court application. The application costs the estate money and the outcome is never certain, which is exactly why the signing ceremony is worth doing properly the first time.

Storing the codicil #

The codicil must be kept with the original will. A probate court treats them as a single instrument; if the executor cannot locate the codicil at the testator's death, the court may presume it was destroyed and ignore it — even if the will itself is intact.

Tell the executor where to find both documents, and update the location reference whenever either document moves.

The "stacked codicil" trap #

A pattern lawyers see repeatedly is testators who add codicil after codicil over the years — three, four, sometimes five amendments stacked on the same original will. Each codicil refers back to the previous version, and the executor ends up working from a chain of documents that needs to be read in the right order to make sense.

Two problems arise. First, any inconsistency between codicils — a beneficiary added in the second codicil and accidentally removed in the third, a percentage that no longer adds to 100 — invites a court application to sort it out. Second, the testator's overall intent becomes harder to demonstrate when challenged, because no single document expresses it cleanly.

A rough rule of thumb used by most Canadian estate practitioners — once a will has been amended twice, the next change should be a fresh will that revokes everything earlier and consolidates the current plan into one document.

What we focus on at It's Simple Will #

We built It's Simple Will for Canadians who want a complete, properly executed plan without the stacked-codicil trap. When a life event changes the plan, our flow walks through a fresh will rather than patching the old one — the difference in cost is small, the difference in clarity is large.

For broader context on how Canadian wills are structured and executed, see our pillar on how to write a will in Canada, and our companion guides on updating your will after a baby and where to store your will in Canada. If you need to dig into the safety net for technical errors, our piece on substantial compliance covers when courts step in to save a botched will.