為什麼?我記得IB的margin可以withdraw cash,難道還不能在另一個股票帳戶用借來的現金買期權?
What’s Actually Allowed in the U.S.
- IBKR May Allow Negative Cash Balance Withdrawals (i.e., Borrowing to Withdraw)
Contrary to earlier assumptions, several users report that Interactive Brokers does allow withdrawals even when the cash balance is negative, as long as margin requirements are satisfied. One user on Reddit confirmed:
“You can withdraw cash and hold negative USD, as long as you have enough funds to cover the maintenance and avoid a margin call.”
- But Negative Cash Means You're Borrowing & Paying Interest
If your account ends up with a negative (debit) cash balance, that means you're effectively borrowing funds. IBKR charges interest on borrowed funds—based on tiered rates and daily calculations.
- No Built-In Safeguard to Avoid Negative Balances in TWS
IBKR’s Trader Workstation (TWS) does not prevent you from executing trades that cause your cash balance to go negative (which triggers a margin loan). That means even if you unintentionally dip into margin by withdrawing or trading, the system will still let you—subject to margin requirements.
- Yes, You Can Use Withdrawn Margin Cash for Anything
When you withdraw cash from a margin account—resulting in a negative cash balance—you’ve effectively borrowed money from your broker. Once those funds are in your own bank or another brokerage, they’re yours to spend or invest however you like. Using margin borrowing in this way is similar to taking out a secured loan. The only restrictions remaining are from the original broker, mainly that you must continue to meet margin maintenance requirements and will be charged interest.
- But You Still Can't Buy Long Options on Margin
Here’s the critical distinction: Borrowed funds don't magically enable you to buy long options on margin at any brokerage.
This is because:
Options are generally non-marginable assets for long positions. To buy a long call or put, you must pay the full premium in settlement cash. You cannot borrow to buy them.
One Reddit comment sums it up succinctly:
“You can buy options with margin, but not on margin.”
This means you may buy options using cash you got from margin, but the options themselves aren’t financed—you're still using cash to pay for every part of it.
So even if you withdraw margin cash, once you deposit it into another brokerage, you’ll need to use that cash to pay for any long options—there's no leveraging of those contracts themselves.
Example to Illustrate:
You borrow $5,000 via margin at IBKR, creating a negative cash balance in your account.
You withdraw that $5,000 and deposit it into Broker B.
In Broker B, you cannot borrow further to buy options—you must use the $5,000 in real settled cash to pay for the premiums in full.
Bottom Line
Yes—you can borrow via margin, withdraw the funds, and use them for other purposes. But this does not equate to buying options on margin. To purchase long calls or puts, you must use actual available cash, not borrowed funds. The borrowed money may finance your broader strategy, but the options themselves must still be fully funded with cash.