ACATS requires your US Tax Identification Number (TIN) to match between IBKR and your other broker.
A TIN is a broad category that includes:
- SSN (Social Security Number) — for individuals
- EIN (Employer Identification Number) — for businesses
- ITIN (Individual Taxpayer Identification Number) — for individuals not eligible for an SSN
W-9 Holders (US Taxpayers)
- If you are a W-9 holder, your SSN/TIN on file is submitted automatically as part of your transfer. You will not see this field during submission, and no action is needed on your part.
- The TIN must match both brokers' records.
W-8BEN Holders (Non-US Taxpayers)
- Since most non-US taxpayers do not have a US TIN, IBKR submits an industry-standard placeholder — 999999999 — in its place. This is standard practice across most US brokers.
Important: This placeholder is not related to your local tax ID or national ID number. There is no need to update your SSN/TIN field with your local tax ID, as doing so will not resolve a mismatch and is not required for your transfer to process. No action is needed unless your transfer is specifically rejected for a TIN mismatch (see below).
Why did my transfer reject due to a "Tax ID mismatch"?
In most cases, both firms use the same placeholder (999999999), and no issue arises.
A mismatch typically happens in one of two situations:
- You previously held US residency. Your account at the other broker may still have a real US SSN on file from that time, while IBKR has the placeholder. Since the two values differ, the transfer is rejected.
- Your other broker uses a different placeholder. Not all firms use 999999999. Some assign their own generic value, which will not match IBKR's. If this is the case, please contact customer service to assist for resolution.
How to resolve if you have a US SSN on file with your other broker
Step 1: Confirm with your broker
- Ask your other broker which TIN they have on file for your account. If it is a real US SSN (from prior US residency), you will need to add that same number to your IBKR W-8BEN form.
Step 2: Update your W-8BEN in Client Portal
To update your W8-ben Form:
- Log in to Client Portal
- Click the User menu (head and shoulders icon in the top right corner) followed by Settings
- Then under the Account Settings section find Account Profile
- Click on Profile of the proper user's name
- The available Tax Forms are displayed at the bottom of the window
- Click Update Tax Forms in the bottom right
- Click Continue until you arrive at the W-8BEN form
Find out more about updating tax forms in the Client Portal User Guide.
Step 3: Resubmit your ACATS transfer
- Once you have completed and submitted the updated W-8, you can resubmit the ACATS request online. Please allow 24 hours before you re-submit to update your records.
Step 4: Upon submission of the new ACATS request, please notify IBKR for us to process the transfer with the corrected information.
Please Note
- Your updated TIN will not be visible on the submission screen, but it will be attached to your transfer automatically.