When you withdraw from your Celsius Network wallet, your deposits are always withdrawn first. For example, if you deposit 100 BTC and withdraw 100 BTC after six months, all that would remain would be the interest you earned on that BTC. If you withdraw 25 BTC, 75 BTC would remain in your wallet plus the interest you previously earned. You would then continue earning on the 75 BTC remaining from your deposit, as you do not earn interest on interest since we don't offer compounding interest.