A cash-secured put is a short put where you keep enough cash (or cash equivalents your broker accepts) to buy the shares if you are assigned. You collect a premium for agreeing to buy stock at the strike. If the stock finishes above the strike, the put often expires and you keep the premium. If it finishes below, you may be required to buy 100 shares per contract at the strike—using the cash you set aside.
This is educational orientation for a taxable brokerage account at brokers such as Fidelity, Schwab, Vanguard Brokerage, E*TRADE, or Interactive Brokers—not a strategy recommendation. Assignment mechanics for options generally: Options assignment risk basics. Premium and assignment tax patterns on the call side: Covered call tax basics.
Collateral vs naked (margin) puts
| Style | What the broker typically holds | Main risk framing |
|---|---|---|
| Cash-secured put | Cash ≈ strike × 100 × contracts (broker formulas vary) | You can afford the stock purchase if assigned |
| Margin / “naked” short put | Margin requirement (often a fraction of notional) | Less cash tied up; larger forced-sale / margin-call risk if the stock gaps down |
| Put credit spread | Long put hedges the short put | Defined-risk; still assignment/exercise quirks near expiration |
Brokers label approval levels differently (Level 2, Level 3, etc.). Cash-secured puts are often allowed at a lower options level than uncovered short puts. Read your broker’s options agreement, Reg T / portfolio-margin FAQ, and early-assignment rules before you click sell-to-open.
What assignment actually does
- You buy the stock at the strike (standard U.S. equity option: 100 shares per contract).
- The cash collateral (or margin buying power) funds that purchase.
- Your account now holds shares with a cost basis tied to the strike (premium received usually reduces basis for tax lot purposes—confirm with Options trading tax basics and a tax pro).
- You then own stock risk: further declines are your equity risk, not “just an options trade.”
Early assignment is less common on puts than on calls around ex-dividend dates, but it still happens—especially deep in-the-money puts near expiration. Pin risk and weekend processing still matter; see Options assignment risk basics.
Worked example: cash-secured put on XYZ
Sam wants to buy XYZ if it drops. XYZ trades at $50. Sam sells one put, strike $45, expiring in 45 days, for a $1.20 premium ($120 credit) at Schwab. Cash-secured collateral required is about $4,500 (45 × 100), held in the account.
- If XYZ stays above $45: the put likely expires; Sam keeps ≈ $120 (before commissions) and the $4,500 is released.
- If XYZ closes at $40 and Sam is assigned: Sam pays $4,500 for 100 shares. Effective economic cost is roughly $4,380 after the $120 premium (ignoring fees). Sam now owns stock that can fall further.
If Sam had sold the same put naked on margin with only a fraction of notional reserved, a sharp gap to $30 could trigger a large mark-to-market loss and a margin call—not just a planned stock purchase.
Practical habits
- Size contracts so full assignment cash is money you were willing to use to buy the shares.
- Know your broker’s exercise/assignment cutoff and whether index vs equity options settle differently.
- Do not spend the “collateral” on other trades while the short put is open.
- Track premiums and assignments for Form 1099 / gain-loss reports (Filing taxes for beginners orientation).
- Compare put-writing to simply placing a cash limit buy—premium income is not free; you take downside obligation.
- Keep beginner portfolio construction boring first: Investing basics for beginners.
Covered-call assignment (stock called away) is the mirror problem on shares you already own: Covered call assignment tax basics.
Checklist
- Confirm options approval level allows cash-secured puts before you sell.
- Reserve full purchase cash (or understand margin math if you intentionally use margin).
- Read early-assignment and expiration-day procedures for your broker.
- Plan what you will do with shares if assigned (hold, sell, write calls).
- Log premiums and trade confirms for tax season.
- Treat short puts as a buy commitment, not “free income.”
Educational only. Not tax, legal, or investment advice. Options can involve substantial risk of loss, including loss greater than the premium received when short. Collateral, margin, and assignment rules vary by broker and product; confirm with current OCC materials, your broker, and a qualified professional.