Most people only look at spreads and overnight costs when calculating transaction costs, but ignore the costs of funds entering and exiting. This article dissects the channel fees, exchange rate conversion and time-point costs of deposits, the handling fees of withdrawals, the arrival time and the transaction lot threshold, analyzes the accumulation of exchange rate differences and the hidden costs of frequent deposits and withdrawals, and provides ways to save money by comparing channel rates, seeing the withdrawal rules clearly, planning the rhythm of funds on a periodic basis, and including channel costs in the general ledger.