Forex: Cannot trade Forex on margin. This means that each Forex trade must settle before a new currency can be traded. It is difficult to AutoTrade Forex without margin. US residents cannot trade forex at IB regardless of the type of account.
Futures: Can trade futures on margin if account is designated as a margin account. IRA clients who use Interactive Brokers will see a higher margin requirement (3x higher) on futures positions than if carried in a non-retirement account.
Options: Limited to option plays that do not borrow, they are actually treated as a cash account (see below).
Reg T Margin: IRA cannot borrow cash i.e. have a debit balance or short stocks.
Cash (no margin): Full payment required for all call and put purchases. Covered call writing is allowed, but the underlying stock must be available and is then restricted. Naked put writing is allowed, but the funds must be available and then are restricted. Cash from the sale of options is available one business day after the trade date.