This is not mandatory. The fixed investment of the fund is to deduct money from the bank card regularly every month, and the deducted money is to buy the fund. As long as there is a deductible amount in the card, there are many kinds of funds, including capital preservation type (zero-risk micro-return), bond type (low-risk low-return) and stock type (high-risk high-return). If you can't deduct the money for two consecutive months, the fund company will automatically transfer the previously deducted money to your bank card. As for the principal, if the fund makes a profit, it will protect the capital and make a profit, and if it loses the principal, it will also lose money. Generally speaking, the fixed investment of the fund is zero deposit and lump sum withdrawal, and many a mickle makes a mickle!