When you sell a put option, a cash premium lands in your brokerage account right away, your broker sets aside collateral to cover a potential stock purchase, and you take on a binding obligation to buy 100 shares of the underlying stock at the strike price if the option holder exercises. That obligation stays open until the contract expires, you buy it back, or you get assigned. The premium is yours no matter what, but if the stock drops far enough, the shares you’re forced to buy can be worth much less than what you pay for them.
The Premium Lands in Your Account Immediately
The moment your sell order fills, the premium is credited to your account as cash. Not a paper gain, not an unrealized profit. Real money, visible in your balance that day. The size of the credit depends mostly on two things: how much time remains until expiration, and how volatile the underlying stock is. A put expiring in 45 days on a jittery biotech will pay considerably more than one expiring next week on a utility, because the buyer is paying for more uncertainty.
That cash stays yours regardless of what the stock does next. If the stock tanks and you’re assigned, the premium offsets part of your loss. If the stock holds up or rises, the option expires worthless and the premium is pure profit.
Collateral Your Broker Locks Up
Brokerages will not let you sell a put without proof you can afford to buy the shares if assigned. How much they lock up depends on your account type.
In a cash account, a cash-secured put requires the full purchase price set aside for the life of the trade: strike price times 100. Sell a $50 put, and your broker holds $5,000 in cash or a money market fund until the contract closes or expires. Federal Reserve Regulation T governs the credit rules brokers must follow for these positions.1eCFR. 12 CFR Part 220 – Credit by Brokers and Dealers (Regulation T)
In a margin account, the collateral requirement is lower but more complex. FINRA Rule 4210 sets the minimum maintenance standards, and the typical formula for a short put involves depositing the premium received plus a percentage of the underlying stock’s value, minus any out-of-the-money amount, subject to a minimum floor.2FINRA. 4210. Margin Requirements The exact percentage depends on the stock’s concentration and volatility. If your account equity dips below the required level, you’ll face a margin call, and your broker can liquidate positions to cover the shortfall without waiting for your approval.
Most platforms show a “buying power effect” that tells you exactly how much capital a specific sale will tie up. That collateral stays frozen until you close the position or it expires.
Your Obligation to Buy the Shares
Selling a put creates a binding obligation to purchase 100 shares of the underlying stock at the strike price if the option holder exercises.3The Options Industry Council. Options Basics The strike is fixed when the trade opens. It doesn’t change if the stock craters 50% the next day. You are telling the market: I will buy this stock at this price if anyone wants to sell it to me at that level.
The Options Clearing Corporation stands between you and the buyer as the guarantor of every contract. Once assigned, the purchase happens whether you want it to or not. The contract stays active until it expires, you buy it back in a closing transaction, or you get assigned.
What Happens at Expiration
Standard monthly equity options stop trading at the close of business on the third Friday of the expiration month. Weekly options expire every Friday. Either way, the outcome depends on where the stock sits relative to your strike when trading ends.
If the stock finishes above the strike, the put is out of the money and expires worthless. No shares change hands, your collateral is released, and you keep the full premium. This is the outcome put sellers root for.
If the stock finishes below the strike by $0.01 or more, the OCC’s Exercise-by-Exception process automatically exercises the option unless the holder instructs otherwise.4Cboe. RG08-073 – OCC Rule Change – Automatic Exercise Thresholds You’ll see 100 shares deposited into your account and cash deducted at the strike price. Under the current T+1 settlement standard, the transaction typically finalizes the next business day.5U.S. Securities and Exchange Commission. Shortening the Securities Transaction Settlement Cycle – A Small Entity Compliance Guide Shares usually appear in your account by Saturday morning.
Your actual loss on assignment isn’t the full difference between the strike and market price. The premium you collected offsets part of it. Sell a $50 put for $2.00, stock closes at $46, and your net cost on the shares is effectively $48 each.
Early Assignment
Early assignment happens when the option holder exercises before expiration. All standard equity and ETF options are American-style, so the holder can exercise any time. In practice, early assignment on puts is uncommon when the option still has meaningful time value, because exercising early throws that value away. When a put is deep in the money with little time value remaining, the holder may decide the cash from exercising is worth more than continuing to hold the contract.
Interest rates play a role. A put holder who exercises early gets cash sooner by selling stock at the higher strike price, and that cash can earn interest. When rates are elevated, early exercise becomes somewhat more attractive on deep in-the-money puts. Your broker may apply its own internal allocation to decide which customer accounts receive the assignment, either random selection or first-in, first-out. The end result matches expiration assignment: cash leaves, shares arrive, and settlement follows the standard T+1 cycle.6FINRA. Understanding Settlement Cycles: What Does T+1 Mean for You?
Maximum Loss and Breakeven
The worst case for a put seller is the stock going to zero. Your maximum possible loss is the strike price minus the premium received, multiplied by 100. Sell a $50 put for $2.00, and the most you can lose is ($50 − $2) × 100 = $4,800. That’s a lot of money for a trade that brought in $200, which is why position sizing matters so much.
Your breakeven at expiration is the strike price minus the premium. In that same example, breakeven is $48. Above $48, you’re profitable. Below $48, losses accumulate dollar for dollar until the stock hits zero.
Compare that to simply buying the stock at $50, where the maximum loss would be the full $5,000. The put seller’s maximum loss is slightly lower because of the premium cushion, but the premium also caps the upside. If the stock rallies to $70, a stockholder gains $2,000 while the put seller just keeps the $200. Put selling wins small and often, and loses big and occasionally.
Closing or Rolling Before Expiration
You don’t have to hold a short put until expiration. A “buy to close” order ends your obligation by purchasing the same contract you originally sold. If the stock has stayed flat or risen and time has passed, the put will likely be cheaper than what you sold it for, and you pocket the difference. If the stock has dropped, buying it back costs more than you received, locking in a loss. Sometimes taking a small loss beats waiting to see if things get worse.
Rolling closes the current position and simultaneously opens a new one. You might roll to a later expiration to collect additional premium and give the stock more time to recover, or roll down to a lower strike to reduce assignment risk. Rolling isn’t free. It usually involves paying a small net debit or receiving a reduced credit, but it can be useful when the trade has gone sideways and you still like the stock.
Many experienced put sellers set exit rules before entering: buy to close at 50% of maximum profit to free up capital, or buy to close if the loss reaches a preset amount. Rules made in advance keep emotion out of the decision when the stock is moving against you.
How the Premium Is Taxed
The IRS does not tax the premium when you receive it. Income is deferred until the contract resolves through expiration, assignment, or a closing transaction.7Internal Revenue Service. Publication 550 – Investment Income and Expenses How it resolves determines the treatment:
- If the option expires worthless, the premium is reported as a short-term capital gain no matter how long the contract was open. Federal statute requires this treatment, always as if the asset was held for one year or less.8Office of the Law Revision Counsel. 26 U.S. Code 1234 – Options to Buy or Sell
- If you’re assigned, the premium reduces your cost basis in the shares you acquire. Sell a $50 put for $2.00 and get assigned, and your cost basis is $48 per share. The premium itself isn’t taxed at assignment; it only matters when you eventually sell the shares, reducing taxable gain or increasing deductible loss.7Internal Revenue Service. Publication 550 – Investment Income and Expenses
- If you buy to close, the difference between the premium received and the price paid to close is a short-term capital gain or loss.8Office of the Law Revision Counsel. 26 U.S. Code 1234 – Options to Buy or Sell
Report expired or closed options on Form 8949. Your broker will issue a Form 1099-B reflecting the transaction, though the timing depends on whether the option was closed within the tax year or carried over.9Internal Revenue Service. Instructions for Form 1099-B (2026)
The Wash Sale Trap
If you sold shares of a stock at a loss and then sell a put on that same stock within 30 days, or get assigned shares through a put within 30 days of the loss sale, the wash sale rule can disallow your loss deduction.10Office of the Law Revision Counsel. 26 U.S. Code 1091 – Loss From Wash Sales of Stock or Securities The statute defines “stock or securities” to include contracts and options, so entering a put counts as acquiring a position in the underlying stock for wash sale purposes. The disallowed loss gets added to the basis of the newly acquired shares, so you don’t lose it permanently, but you can’t use it to offset gains on this year’s return. This catches active traders more often than you’d expect, especially those selling puts on names they’re already trading in and out of.