As part of reaching Complete status, you'll be asked to make an initial deposit of HKD 10,000 or equivalent. This isn't an arbitrary requirement — it's part of the Hong Kong SFC's remote onboarding rules for platforms like EVIDENT.
The remote-onboarding regulation requires Professional Investor platforms to confirm an investor's ability to fund their account before that account is fully activated. The initial deposit serves that purpose, and is a one-time step during your account completion.
The amount stays in your wallet as a usable cash balance — it isn't a fee. You can use it toward future investments, swap it into another currency, or withdraw it once your account is fully active.

