I want to clarify that only U.S. residents are permitted to designate beneficiaries for their IB brokerage account. With that in mind, the Executor of your estate should notify IBKR Client Services regarding a deceased account via email to
estateprocessing@interactivebrokers.com
At that time, general information will be taken and the executor will be provided with information on how to proceed.
Once IBKR has been notified of the death of an individual account holder, the account will be classified as a deceased account and activity (e.g., trading, transfers) is generally prohibited until legal authority is established.
If the recipient(s) of the assets decide to open an account at IB, and the assets in your current account are transferred to the recipient account, yes, the margin loan can also be transferred to the recipient accounts.
Regards,
Wayne B
IBKR Client Services