Margin against a cash account for option sellers
A cash-secured put ties up the strike times 100. The same put under exchange margin rules ties up about a seventh of that, which means the same $50,000 can carry seven times the obligation. Nothing about the risk per contract changes. What changes is that a bad six weeks can now generate a demand for money you do not have.
The word "secured" is doing a lot of work in "cash-secured put." It describes the funding, not the risk.
The two requirements, side by side
Cash account: the strike times 100, in full, for the life of the trade. No exceptions and no formula.
Margin account: whatever the exchange says. Regulation T, 12 CFR 220.12 (Cornell LII) sets 50 percent for buying stock and then hands listed options straight to the exchanges, which is why the operative number for a short put is Cboe, Strategy-Based Margin requirements rather than anything in Regulation T. The formula is 100 percent of the proceeds plus 20 percent of the underlying value less the amount the option is out of the money, floored at proceeds plus 10 percent of the strike.
| Ticker | Strike | Cash secured | Margin requirement | Leverage |
|---|---|---|---|---|
| AMD | $106 | $10,600 | $1,412 | 7.5x |
| MU | $83 | $8,300 | $1,117 | 7.4x |
| KMI | $26 | $2,600 | $427 | 6.1x |
| INTC | $21.50 | $2,150 | $324 | 6.6x |
| T | $21 | $2,100 | $320 | 6.6x |
| WBD | $10.50 | $1,050 | $154 | 6.8x |
| Total | $26,800 | $3,754 | 7.1x |
$50,000 of cash supports 1.9 copies of this book. $50,000 of margin supports 13.3.
These are exchange minimums. Your broker is free to demand more and most do, which is the only thing standing between a retail account and the last row of the table below.
Nothing about the risk changed
Worth saying plainly, because the leverage numbers hide it. The AMD put obliges you to buy 100 shares at $106 whether you posted $10,600 or $1,412. The obligation is identical. The maximum loss is identical. The only difference is how much of it you have already funded.
Which means the margin version is not a cheaper trade. It is the same trade with the funding moved to a place where somebody else can call it in.
The crash cycle, at five leverage levels
Cycle 3 again: AMD down 23.8 percent, MU down 23.5, INTC down 21.0, and five of six puts assigned. Per copy of the book that was a $2,902 paper loss, and the margin requirement per copy went from $3,754 to $8,357 as the puts went in the money and the out-of-the-money credit in the formula disappeared.
| Copies | Contracts | Requirement at the open | Equity after the cycle | Requirement after the cycle | Margin call |
|---|---|---|---|---|---|
| 1, cash account | 6 | $26,800 of cash | $47,098 | none, prepaid | none |
| 1 | 6 | $3,754 | $47,098 | $8,357 | none |
| 2 | 12 | $7,508 | $44,196 | $16,715 | none |
| 3 | 18 | $11,262 | $41,294 | $25,072 | none |
| 5 | 30 | $18,770 | $35,490 | $41,786 | $6,296 |
| 13 | 78 | $48,802 | $12,274 | $108,645 | $96,371 |
Read the 13-copy row slowly. The account started at $50,000, used almost all of it as margin, lost $37,726 in six weeks, and then faced a requirement of $108,645. There is no version of that where you choose what to sell.
And read the top row too. The cash account held the same six positions through the same six weeks, was down $2,902 on paper, and was never asked for a dollar. It could sit there and let the recovery happen, which is exactly what it did: those five assignments went on to produce most of the year's $7,168.
The requirement moves against you twice
This is the mechanism that catches people, and it is worth spelling out.
The formula subtracts the out-of-the-money amount. When AMD is at $126 and the strike is $113, that subtraction is $1,300 and the requirement is small. When AMD is at $96 the option is $17 in the money, the subtraction is zero, and the option's own value is now $1,700 of the requirement instead of $278.
So the requirement roughly doubles at the same moment your equity falls. Both sides of the ratio move the wrong way together, which is why margin calls arrive in clusters and never gradually.
Then, if you are assigned, the shares themselves need maintaining. FINRA Rule 4210, Margin Requirements sets 25 percent of market value on long stock, and the five assigned positions in this book were $22,460 of stock at the settle prices, so that is another $5,615 per copy to carry.
What a cash account gives up, honestly
It is not all upside, and two costs are real.
Idle collateral. $26,800 sat against these six puts and $23,200 sat doing nothing. In a margin account that capital is available, which is the entire argument for margin and it is a good one.
Settlement mechanics. A cash account has to have settled funds, so cash freed by an assignment or a closing trade is not always immediately reusable. It is an annoyance rather than a risk.
What it buys is the thing this whole page is about: nobody can force you to sell at the bottom of cycle 3. Cluster E works the same comparison on a single contract, and the conclusion there and here is the same. The leverage is real, the arithmetic is public, and the reason to decline it is that the crash cycle arrives on a schedule nobody publishes.
One rule that is not worth worrying about: the pattern day trader threshold. It applies to day trading, and nothing in this book was held for less than 43 days.
OptionsKing scores every candidate strike on a deterministic 0 to 100 scale, blends that score with the return on the capital the trade ties up, and shows you the highest-ranked handful. There is no minimum score. How it works covers what the ranking does and does not tell you.
Questions people actually ask
Do I need a margin account to sell puts?
No. A cash account can sell puts fully secured by cash, at the strike times 100 per contract. A margin account lets the same contract be held for roughly a seventh of that under exchange minimums, which is leverage rather than a different trade.
How much margin does a short put require?
Under the published exchange formula, 100 percent of the option proceeds plus 20 percent of the underlying value less the out-of-the-money amount, floored at proceeds plus 10 percent of the strike. On the worked book that was $3,754 against $26,800 of cash, about 7.1 times the leverage. Brokers routinely require more.
What actually triggers a margin call on short puts?
Both sides of the ratio moving at once. In the worked crash cycle equity fell while the requirement more than doubled, because the out-of-the-money credit in the formula disappeared and the option value replaced it. Five copies of a six-position book produced a $6,296 call.
Is a cash account safer for selling options?
It removes forced selling, which is the risk that actually ends accounts. The cost is idle collateral: $23,200 of the worked $50,000 earned nothing while six puts were open.
Sources
Rules and thresholds above were checked against these documents on August 4, 2026. Exchange and broker rules change. Confirm anything you are about to act on with your own broker.
Keep reading
Do the math on your own trade
Every price in this article is an illustrative worked example, not a quote. Read Running the book for the rest of the series, and the disclaimer before you act on any of it. Selling options carries real risk of loss, and the loss can be far larger than the premium you collected.