You sold a call option on a stock you own. It was supposed to be a nice way to earn some extra "rent" on your shares. But, all of a sudden, the stock price soared and now the option strike price is less than the current price, making it in-the-money (ITM).
Just like that, the abstract world of options contracts becomes very real. So, what happens now?
While buying an option is as simple as a few taps on your phone or clicks of a mouse, the back-end mechanics of assignment and exercise can seem like a mystery.
This guide walks through what assignment and exercise mean, when they happen at expiration and early, how T+1 settlement changes your timeline, how to reduce your risk of a surprise assignment, and how the CRA taxes the outcome.
Assignment vs. exercise: two sides of the same coin
Options assignment is the seller's obligation to fulfill an options contract that the buyer has chosen to exercise. To see how that works, start with the two parties in every options trade — the buyer and the seller:
Party 1 — the buyer, the person with the right.
Party 2 — the seller, the person with the obligation.
When the buyer decides to use their rights or the seller has to meet their obligations is where exercise and assignment come in.
Exercise: this happens when the buyer (long position) chooses to enforce the contract. For example, if you bought a call and the stock is soaring, you might choose to "exercise" your right to buy those shares at the strike price.
Assignment: this happens when the seller (short position) is obligated to fulfill the contract the buyer has exercised. For example, if you sold a call and the buyer decides to exercise, you're "assigned." You have to deliver those shares now.
An easy way to think of it is like a restaurant. The customer (buyer) chooses to exercise their right to order the daily special. The kitchen (seller) is then assigned the duty of cooking it.
The journey of an assignment
When a buyer decides to exercise, the request doesn't go directly to you. It follows a very specific but randomized path:
The buyer tells their broker that they want to exercise the option.
The clearing house receives the request — the Canadian Derivatives Clearing Corporation for Canadian options, or the Options Clearing Corporation for U.S. trades.
Using a random selection process, the clearing house picks a broker with clients that hold short positions of the same option.
The broker then uses a random selection process to pick which client gets assigned.
It works a bit like a lottery. If you sold the same call as 1,000 other people but only 100 were assigned, you might be one of those who isn't.
But it's important to know that there are different styles of options, which affects how they're exercised and assigned.
American vs. European style
Most stock and ETF options in North America are "American style."
This means they can be exercised or assigned at any time before they expire.
"European style" options (usually found on large stock indices such as the S&P/TSX 60) can only be exercised on the very last day.
What happens at expiration?
Most of the time, this happens right at the finish line.
There's a common standard called "automatic exercise." This means if an option is $0.01 or more ITM at the closing bell on the expiry date, it's usually exercised automatically by the clearing house.
For the buyer (long)
If your option is ITM, your broker will automatically buy (for a call) or sell (for a put) the shares for you.
But you need the cash or the shares ready. For example, if you don't have the buying power to handle 100 shares of a $200 stock, you might run into margin issues. Your broker might sell the option on your behalf before the market closes to prevent a shortfall.
If you don't want your broker to take action on your behalf, you typically need to give them specific instructions not to.
For the seller (short)
If the option you sold is ITM, expect to be assigned.
On the other hand, if the stock stays below your strike price (for a call), the option expires worthless. You keep the premium, and nothing else happens.
Pin risk
"Pin risk" happens when a stock closes exactly at — or incredibly close to — the strike price at 4:00 PM on Friday. When this happens, you don't know if you'll be assigned or not.
If the stock moves $0.05 in after-hours trading, a buyer might still decide to exercise, and you could wake up Monday morning with a stock position you didn't expect.
T+1 settlement
As of May 2024, Canada and the U.S. moved to T+1 settlement for stocks. This means that when you buy or sell a stock, the ownership and the cash change hands just 1 business day later.
How this affects you
Options have always settled T+1. But the shares resulting from an assignment used to take 2 days (T+2) to settle.
Now, everything moves at the same speed. So, if you're assigned on a Friday, the resulting share trade settles on Monday (assuming there are no holidays).
This creates a much smaller window. Before, you had until Tuesday to "fix" a cash shortfall or deposit shares. Now the window is tighter, and you need your house in order by Monday morning.
Early exercise: why does it happen?
Most assignments happen at expiration, but there is the odd instance where they don't.
Why would someone exercise early? It's usually due to one of these main reasons:
Deep ITM puts: if a put is deep ITM, the buyer might exercise early to get their cash immediately.
Dividends: this is the most common reason for an early assignment on calls.
The ex-dividend trap
If you've sold a covered call, make sure to keep a close eye on the ex-dividend date.
Call buyers often exercise ITM calls just before this date so they can own the shares in time to collect the dividend payment.
If you're short a call option that's ITM and approaching an ex-dividend date, your risk of early assignment increases significantly.
If you're assigned early:
You sell your shares at the strike price. The buyer gets the dividend; you do not.
If you didn't own the shares (a "naked" call), you might find yourself "short" the stock. This means you owe the dividend to the person you borrowed the shares from.
Traders who want to avoid this usually "roll" their position (closing the current one and opening a new one further out) or simply close the trade before the ex-dividend date.
How to reduce your risk of assignment
You can't remove the chance of assignment entirely when you hold a short option, but you can manage it. A few habits keep surprises to a minimum.
Watch ITM options closely. The deeper ITM your short option is, and the closer it gets to expiry, the higher the odds of assignment.
Mind the ex-dividend date. If you're short a call that's ITM as a dividend approaches, close or roll the position before the ex-dividend date to sidestep early assignment.
Close or roll before expiry. Buying back the option closes the trade and ends the obligation. Rolling closes the current position and opens a new one further out in time or at a different strike.
Keep enough cash or shares on hand. If you'd struggle to buy or deliver 100 shares per contract, an assignment can trigger a margin call. Make sure your account can cover the outcome.
Assignment is far from guaranteed. Most options are never exercised, and traders often close positions before expiry. Still, treating every short option as if it could be assigned is the safer mindset.
Tax implications for Canadian traders
When it comes to tax time, it's always best to consult a tax professional for accurate advice. But as a general rule (this is not advice), the CRA treats the money you've made from options by looking at your intent.
Capital gains. If you're an occasional investor, profits from options are usually treated as capital gains. That means only 50% is taxable.
Business income. If you're trading daily, using high leverage, or trading as your main activity, the CRA might view this as business income. That means it's 100% taxable.
The math of assignment
When you're assigned, the premium you originally received isn't taxed as a separate gain. Instead, it's folded into your adjusted cost base (ACB) — the official price you paid for tax purposes — or your proceeds.
Scenario | CRA formula |
|---|---|
| Assigned on a put. You buy shares: the premium you received lowers your ACB of the shares you just bought. | $ACB = Strike Price - Premium Received + Commissions |
| Assigned on a call. You sell shares: the premium you received increases your proceeds. | $Proceeds = Strike Price + Premium Received - Commissions |
| Exercising a call. You buy shares: the premium you paid is added to the ACB of the shares you got. | $ACB = Strike Price + Premium Paid + Commissions |
