AngelList is required to request withholding forms from investors with active investments on the platform, including non-US residents. Without a valid W-8 (or the corresponding information) on file, our funds may be obligated to withhold US taxes at the maximum rate, as opposed to a reduced rate or not withholding at all.
If you have not completed your tax forms, we encourage you to do so from your Tax page: https://angel.co/invest/tax-documents.