In options trading, "margin" also refers to the cash or securities required to be deposited by an option writer with his brokerage firm as collateral for the writer's obligation to buy or sell the underlying security, or in the case of cash-settled options to pay the cash settlement amount, in the event that the option gets assigned.
Margin requirements for option writers are complicated and differ by underlying, strategy and account framework. They are subject to change and can vary by brokerage firm. Writers of calls or puts, alone or in combinations such as spreads, Short Straddles or Short Strangles, should obtain the applicable requirements from their broker and plan for increases if the market moves against them. Margin affects capital committed and funding risk; it is not the trade’s maximum loss.
Margin Requirements Manual
Consult the current FINRA margin rule, exchange requirements and your broker’s house rules. Strategy-based and portfolio-margin accounts can produce different requirements. Historical margin manuals are not a current broker quote.
Margin Calculator
Use your broker’s order preview or margin calculator for the proposed position, including existing holdings. An estimate can change with prices, volatility, concentration or house policy. It does not guarantee that a spread will retain its initial requirement after a leg is closed, exercised or assigned.
Assignment and liquidation
A bounded expiration payoff does not eliminate interim funding needs. Assignment of one leg can create stock or cash obligations before the other leg is resolved. The broker can demand collateral or liquidate positions under the account agreement; do not assume a margin call provides extra time. Futures margin is a separate performance-bond system: see futures margin.
U.S. intraday margin transition in 2026
FINRA’s new intraday margin framework took effect on June 4, 2026, with firms permitted to transition through October 20, 2027. A firm still using the old framework can retain its pattern-day-trader restrictions, including the $25,000 equity requirement. A firm that has transitioned uses position-based intraday requirements without that trade-count designation or $25,000 minimum. House requirements can be higher. Confirm which framework your broker applies; the transition also matters to intraday options activity. See FINRA’s explanation.
Separate the payoff limit from available cash
Consider one $50/$45 put credit spread entered for $1.20. Its matched expiration loss is at most ($5 − $1.20) × 100 = $380 before fees. A broker may initially reserve an amount related to that risk, but the actual requirement depends on account rules and offsets.
If the short $50 put is assigned early, the account purchases 100 shares for $5,000 while the long $45 put remains. That put may still provide economic protection, but the account now holds stock and a long option. The cash movement and broker’s interim capital calculation are not simply the original $380 reserve. Selling stock, selling the put or exercising it produces different execution and time-value consequences.
A separate uncovered position might have $1,500 of buying-power impact at entry and $2,600 under a later broker preview. Those invented figures illustrate a $1,100 increase, not a regulatory formula. Plan liquidity for changing requirements and stress liquidation prices rather than assuming a displayed requirement remains fixed.
The 2026 intraday transition described above was rechecked for this expansion. Confirm whether the broker has migrated and which house rules apply. An options approval level, minimum account equity and the capital requirement of a particular position are different constraints.
