If you're ready to sell cash-secured puts but Thinkorswim's interface looks like a cockpit, you're not alone. Setting up a CSP trade on TOS is straightforward once you know where to click and what settings matter.

This walkthrough is the platform-specific execution guide for our Cash-Secured Puts Playbook. If you're new to CSP strategies, read the playbook first to understand the full framework, DTE selection, and strike/premium trade-offs. Then return here for the exact Thinkorswim steps.

Also recommended: After you execute, use our Rolling Cash-Secured Puts guide to manage your positions as expiration approaches.

Prerequisites: Setting Up Your Account

Before you can sell puts, Thinkorswim needs to know you're allowed to do it.

Log in to your account, then go to Menu → Account Settings → Positions (or Account tab in the mobile app). Look for "Options Trading Level." You need at least Level 2 to sell covered calls or cash-secured puts.

If you only see Level 1, you'll need to apply for higher access through your broker. This is usually instant online.

Cash-secured put selling also requires buying power collateral—TOS automatically reserves the full putStrike × 100 dollars in your account when you place a CSP order. So if you're selling a $50 put, TOS locks $5,000 cash (or margin equivalent). Make sure you have that available before you start.

Step 1: Open the Options Chain

From the Trade tab, type your stock symbol in the upper left. Press Enter. You'll see the stock chart and basic quote.

If you don't see an Options Chain sub-tab, right-click the chart area and select Show Options Chain, or press Alt+O (Windows) or Cmd+O (Mac).

The options chain loads below the chart. You'll see columns for:

Strike price (middle column)
Bid/Ask for calls (left side)
Bid/Ask for puts (right side)
Greeks (delta, theta, gamma, vega) if you enable the columns

Step 2: Select Your Expiration and Strike

This is where DTE discipline kicks in.

At the top of the options chain, you'll see expiration dates (weekly, monthly). Click the expiration you want. Most CSP traders target 14–45 DTE for the best risk/reward tradeoff—enough theta decay to matter, but not so close to expiration that assignment risk or volatility whipsaws catch you.

Once you've picked your expiration, scan the Put side (right half of the chain). Each row is a strike price.

The key metrics are:

Delta: How much the put payout changes if stock moves $1. Aim for 0.20–0.30 delta for CSPs (meaning ~20–30% probability of assignment). Detailed explanation of delta and other Greeks in our Options Greeks Explained guide. For deeper dive on how delta and theta interact across DTE, see Greeks by DTE Reference.
Bid/Ask Spread: The bid is what buyers will pay you; the ask is what sellers want. Tighter spreads (small gap) = easier to fill. Avoid bids/asks that are very wide.
Theta: How much premium decays per day. Higher theta = faster decay = more profit if you hold to expiration.

Select a strike that fits your criteria. Let's say we're selling Apple (AAPL) 45 DTE, targeting a 0.25 delta.

Step 3: Right-Click to Place an Order

Right-click on the Bid price in the Put column for your chosen strike. A menu pops up.

Select Buy to Open (this sounds backward—you're buying puts to open a short position, or equivalently, selling puts to open a CSP).

A trade tickets pops up on the right side. The quantity defaults to 1 contract (= 100 shares obligation).

Step 4: Set Your Order Details

In the trade ticket, you'll see:

Quantity: Usually 1 (one put contract = obligation to buy 100 shares)
Order Type: Default is usually "Market" or "Limit"
Limit Price (if using Limit): Set this slightly lower than the current bid to improve your fill odds (you collect more premium if you're patient). Alternatively, place a limit order at the bid for immediate execution.
Time in Force: Choose Day (order expires if not filled today) or Good Till Close (GTC, expires at end of trading day). For CSPs, Day is typical because you're managing it actively.

Pro tip: Use a limit order slightly below the bid instead of a market order. This gives you 1–2 minutes for the order to fill at a better price. If it doesn't fill, you can re-submit.

Step 5: Review and Confirm

Double-check:

Quantity = 1 contract (or your planned size)
Symbol = correct stock
Action = Sell to Open (or "Buy to Open" in some TOS interfaces—this opens a short put, which is what you want)
Strike & Expiration = correct
Limit Price = slightly below current bid (if using limit)

Once you're satisfied, click Send Order or Confirm & Send.

Step 6: Monitor Your Trade

Once filled, the put appears in your Positions tab. You'll see:

Quantity: -1 (the short puts you sold)
Current Price (mark): The put's current market value
P&L: Your unrealized profit/loss

For a CSP, watch two things:

Theta decay (your friend): Each day that passes, the put decays. If the stock doesn't move much, you're winning—theta accelerates into expiration.

Stock movement way down: If the stock gaps down hard, your put goes deep in the money (large negative delta). This means assignment is now likely. You can:

Hold to expiration and take assignment (buy 100 shares at your strike price)
Close early by clicking the put position and selling to close at the current ask (cut losses before assignment)
Roll the position (buy back the current put, sell a new put at the same or lower strike, further out in time). Learn more in our Rolling Cash-Secured Puts guide.

Most CSP traders let profitable trades ride to expiration (capturing full theta), but exit early if the profit is threatened.

Step 7: Rolling (Optional)

If your stock is approaching expiration and you got assigned (or you want to avoid it), you can roll the position.

Right-click the put in your Positions tab. Select Close. TOS shows you the current bid/ask to close. Once closed, immediately go back to the options chain, pick a new strike and expiration, and repeat steps 3–5.

The net credit/debit of closing + selling the new put is your rolling credit/debit. Aim for a credit or small debit—you're extending the duration and moving to a safer strike.

Key Thinkorswim Settings for CSP Success

Enable the Greeks

Right-click the column headers in the options chain. Select Column Filter or Customize Columns. Add:

Delta (your probability tool)
Theta (your decay timer)
Gamma (your edge during big moves)
Vega (your volatility sentiment)

These give you the data to choose smart strikes.

Set Alerts for Assignment Probability

This isn't automatic, but you can manually track it. Thinkorswim shows delta for each strike. If your short put's delta approaches 0.50 or higher, assignment is likely. Set a phone alert reminder to check the position on those days.

Use the "Analyze" Tab for Profit/Loss Scenarios

Before you sell, click the Analyze tab at the top of your trade ticket. Thinkorswim builds a profit/loss chart showing:

Your max profit (premium collected)
Breakeven (strike – premium)
Loss if stock crashes

This visual is a reality check: can you live with catching that underlying if you're wrong?

DTE Calendar: What to Watch

As your CSP approaches expiration:

14–7 DTE: Theta accelerates. Check your position daily. If it's profitable, ride it out; you're not far from full premium.

7–2 DTE: Stock whipsaws matter more (gamma explodes). Be ready to roll or close if the stock moves hard.

2 DTE – Expiration: Last trading day is usually the day before expiration (Friday for weeklies). This is your last chance to roll or close. After the market close, your position is settling (either profit captured or assignment incoming).

The Day After Expiration: If you were assigned, 100 shares land in your account at your strike price. You now own the stock.

Avoiding Common Thinkorswim Mistakes

Mistake 1: Forgetting to enable options level → You can't place the order. Check Account Settings first.

Mistake 2: Picking a strike with no liquidity → You see a bid/ask but it's very wide. Your order fills poorly or not at all. Stick to strikes with tight spreads (bid-ask < $0.20).

Mistake 3: Using a market order at the ask → You overpay for the order to fill fast. Use a limit order slightly below the bid instead.

Mistake 4: Not reserving cash → Thinkorswim requires the full collateral (strike × 100). If you don't have it, the order will be rejected. Plan ahead.

Mistake 5: Ignoring delta and greeks → You sold a 0.70-delta put thinking it's safe. It's actually 70% likely to be assigned. Stick to 0.20–0.30 delta for conservative CSPs.

Linking Your CSP Trades Across Platforms

Once you're comfortable on Thinkorswim, you can use the same strategy on Interactive Brokers (if you want cheaper commissions) or Schwab (if that's your brokerage). The steps are the same: options chain, select strike, right-click, set limit price, confirm. See our How to Sell CSP on Interactive Brokers guide if you decide to switch platforms.

Many traders maintain positions on multiple brokers. The DTE and delta discipline stays the same—Thinkorswim just happens to be the most approachable platform for learning.

Wrapping Up: Your First CSP on Thinkorswim

Pick expiration: 14–45 DTE
Choose strike: 0.20–0.30 delta (safer) or 0.30–0.40 (aggressive)
Place limit order: Slightly below bid for a better fill
Monitor daily: Watch for assignment signals, theta decay
Decide at ~2 DTE: Hold, close, or roll

The best part? Once you've done this twice, it becomes muscle memory. You're no longer fighting the platform—you're just executing the same repeatable CSP process on a tool that's designed to make it easy.

Next step: Start with one contract on a liquid stock (AAPL, MSFT, SPY, QQQ). Sell at 0.25 delta, 30 DTE. Monitor for 2 weeks. By expiration, you'll have a real-world sense of how fast theta moves and how realistic assignment is for you. For help choosing the right stocks to trade, check out Best Stocks for Selling Cash-Secured Puts.