Why is the amount I can withdraw less than my wallet balance?

The proceeds from the sale of US stocks will be reflected in your withdrawable balance on the later of the following two domestic business days (the domestic trade date) or the US settlement date (the US settlement date).

Furthermore, if you have a completed sell order before the domestic settlement date, the withdrawable balance may be lower than the actual settlement amount due to the collection of taxes (capital gains tax) in your specified account.

Once the domestic settlement date arrives, the amount of tax to be collected or refunded will be finalized and reflected in your withdrawable balance.

However, if the domestic settlement date is the first business day of the month, the reflection in your withdrawable balance will occur on the next business day (the second business day of the month).

Please also refer to the "About Withdrawals" section on the Alpaca Securities website.

https://sec.alpaca.ai/guide/common/about-withdrawal/