Assignment is when the option buyer exercises their right and you, as the seller, fulfill your obligation. For put sellers, that means buying 100 shares at the strike price. It sounds scary, but here's the first thing to know: only about 7–10% of all options are ever exercised. The vast majority — 55–60% — are closed before expiration. Another 30–35% expire worthless. Assignment is the exception, not the rule.
You'll hear that 80–90% of options expire worthless. That's wrong. It confuses "not exercised" with "expired worthless." The actual breakdown: ~10% exercised, ~55–60% closed through offsetting trades before expiration, ~30–35% expire worthless. The myth partly comes from a futures options study (1997–1999) that found 76.5% expired worthless — but futures options behave differently from equity options, and that period coincided with a strong bull market that devastated put values. Don't apply those numbers to stock options.
It's a two-step random lottery. When someone exercises their option, their broker sends a notice to the OCC (Options Clearing Corporation). The OCC randomly assigns it to a clearing firm that has short positions in that option. The clearing firm then randomly assigns it to one of their customers. Neither you nor your broker controls who gets assigned — it's genuinely random.
Assignment processing happens overnight. You typically discover it the next morning before market open. Your short put disappears from your account and is replaced by 100 shares of stock at the strike price. Cash equal to Strike × 100 is debited from your account.
Any option that's in-the-money by $0.01 or more at expiration is automatically exercised — unless you specifically tell your broker not to. This is called "Exercise by Exception." The closing price used is the last regular-hours trade at or before 4:01:30 PM ET. So if you have a short $50 put and the stock closes at $49.99, you're getting assigned automatically. No action needed from the buyer.
Early assignment — exercise before expiration day — is uncommon for puts. It's more relevant for call sellers around ex-dividend dates. A call holder might exercise the day before the ex-dividend date if the dividend exceeds the remaining time value of the option. The logic: they want to own the shares before the cutoff to collect the dividend.
For puts, the early exercise decision is driven by interest rates. Exercising a put generates cash from selling stock, and that cash earns interest. In low-rate environments, there's almost no incentive. With higher rates, deep in-the-money puts with little time value remaining might be exercised early — but this remains statistically rare for OTM put sellers.
If you sell 16-delta puts and manage at 50% of max profit, the probability of early assignment is well below 1%.
Short put assigned: 100 shares per contract are purchased at the strike price. Cash is debited (strike × 100). The put option disappears and you now own stock. Example: assigned on a $45 put → $4,500 debited, 100 shares appear.
Short call assigned (covered call): Your shares are sold at the strike price. Cash equal to strike × 100 is credited.
If your account doesn't have enough cash to cover the assignment, your broker issues a margin call. Multiple brokers — including Schwab, Fidelity, and Public — begin attempting to close at-risk positions as early as 3:30 PM ET on expiration day if your account appears under-resourced. This is why proper position sizing matters — you should always have the cash to cover assignment.
Since May 28, 2024, exercised equity options settle on T+1 — the next business day. Previously it was T+2. This means shares and cash change hands one day after exercise. The compressed timeline also eliminated "late exercise" entirely — there's no longer a mechanism to submit exercise notices after the standard deadline.
When a put is assigned, the premium you collected is not reported as separate income. Instead, it's absorbed into the cost basis of the shares you acquire. The IRS is clear on this:
Holding period starts fresh. The clock for long-term capital gains treatment begins the day after assignment — not when you originally sold the option. If you sold the put six months ago and get assigned today, you need to hold the shares another 12+ months from today for long-term treatment.
If the option expires worthless: The premium is reported as a short-term capital gain regardless of how long the option was open.
If you sell stock at a loss and buy a call on the same stock within 30 days, it's a wash sale — the loss is disallowed. Being assigned on a put (acquiring shares) within the 61-day window around a loss sale on the same stock also triggers a wash sale. Traders who repeatedly sell puts, get assigned, sell shares at a loss, and sell new puts can create cascading wash sale complications. If you roll positions regularly, this is worth discussing with a tax professional.
Assignment risk is low in aggregate — about 7–10% of all options, and far less for OTM puts managed early. But when it strikes, it arrives without warning and settles by the next business day. The preparation is simple: only sell puts on stocks you'd own at that price, always have the cash to cover assignment, and track your cost basis (Strike − Total Premium Collected) so you know your real entry price. For Cash-Secured Put sellers who've done their homework with tools like ThetaLoop's X-Ray, assignment isn't a disaster — it's the start of the Wheel Strategy.