Deduct the subscription fee from the total subscription amount instead of drawing extra money, that is, adopt the so-called "internal deduction method" trading mode. According to international practice, in the developed countries and regions such as the United States, China and Hongkong, most funds use "internal deduction method" to extract fund transaction costs. Open-end funds are priced at unknown prices, and there is only one transaction price throughout the day, that is, the net value of fund shares after the closing of the subscription day plus or minus the corresponding handling fee. In this case, if the method of "transaction price+handling fee" is adopted, if the fund balance of the investor's trading account is insufficient because the price is unknown, then the investor's trading on that day will be invalid, and he can't reapply until the next open day, which will undoubtedly affect the timeliness of investment and even cause undue losses to investors.