Fidelity Net Benefits accounts are not eligible to be transferred via ACATS. Fidelity has a form (SPS Transfer) that you would need to fill out and send back to Fidelity. Fidelity may then initiate the transfer.
Then, at IBKR, you may submit an incoming transfer notification in Client Portal:
- Login to Client Portal
- Click Transfer & Pay followed by Transfer Positions
- Select Incoming
- Select the Region ("United States") of the delivering firm
- Select Free of Payment Transfer of US Securities