Linking the accounts you created in the Invest section of Portfolio123 is very easy.
When you create a new invest account you will be asked if you wish to link the account to your brokerage account. You can also link an account later by accessing the account properties from the lines menu in the top left of the page.
You will need to agree to IB terms and provide a picture ID. The approval process takes about 2-3 business days. If you are having trouble with our integrated linking process you can send the agreements and picture ID to Interactive Brokers directly by emailing them at firstname.lastname@example.org . For individuals use this form. For organizations use this form.
Currently only Interactive Broker accounts are supported. The ability to link to other brokers is underway.