Bank prefilled W-8BEN with suspicious U.S. TIN (starts with 900) — is this normal?

Hi everyone,

I live in Switzerland and recently received a pre-filled W-8BEN from my bank (Morgan Stanley). I noticed they put a U.S. Taxpayer Identification Number (TIN) on the form: 900-XX-XXXX.

• I never applied for an SSN or ITIN.
• A Morgan Stanley rep told me this number exists because I also have a U.S. bank account with Citibank.
• From what I can tell, numbers starting with 900 are usually ITINs, but this one doesn’t seem to match the valid IRS ranges — it looks more like a placeholder/dummy number.

My questions:

1. Has anyone else had their bank prefill a W-8BEN with a “fake” or placeholder TIN?
2. Should I leave this field blank and only provide my Swiss tax number (AHV/AVS) on line 6?
3. Is there any risk if the bank continues reporting this number to the IRS?

I want to avoid filing forms with an incorrect U.S. TIN that isn’t really mine.

Thanks in advance for any insight from others who’ve dealt with this!