What are the margin implications of option assignments?

You should review your positions prior to expiration to determine whether you have adequate equity in your account to exercise your options. You should also determine whether you have adequate equity in the account if an in-the-money short option position is assigned to your account. You should also be aware that short options positions may be exercised against you by the long holder even if the option is out-of-the-money…

To sell an option against a long option already in a margin type account simply create a sell order and if the account has enough available funds to meet any change in the account's margin requirements the order is accepted. The short option will automatically be margined with other options on the same underlying. …

A Short Sell order will be accepted and can possibly trade if you have a margin type account and there is sufficient Available Funds to meet any change in the account's margin requirements. If If you do not want the ability to sell short, you would need to have a Cash type account as Cash accounts cannot borrow shares of stock to naked short sell, be short naked Call options or short non-cash secured Put options. Cash accounts are restricted from holding a short balance in any currency as this would also constitute a loan from IBKR…

IBKR computes a value referred to as Net Liquidation Uncertainty to account for the dislocation that takes place between stock and option prices when stocks trade but options do not.  This value is aggregated with Equity with Loan Value…