Multiple accounts maintained in the same name and taxpayer ID number are grouped for the purposes of applying the maximum client protection limits of $500,000 by SIPC and $29.5 million under Lloyd’s supplementary protection. However, if you hold accounts with IBKR in separate capacities (for example, an account in your name, a trust account of which you are the trustee or a beneficiary, and/or a joint account), then each account would be protected by SIPC and the supplementary protection up to the stated limits.
Find more information on investors with multiple accounts on the SIPC website.