You only pay tithing on profit of your initial investment. Let's say you borrow 10K from a lender, so your initial investment is 10K: Case 1: If you sold your stocks when you stock value is above your initial capital then you will have a profit Therefore you WILL pay tithing. Let' say you sold all your stocks with a value of 13K total, then your profit is 3K. Your tithing is 300 Case 2: If you sold your stock at loss, then you did not make a profit therefore you WILL NOT pay tithing. Let's be clear losses include profit and losses combine from many stocks. If you gain 20% in stock A, and lose 50% in stock B (assuming all amounts are equal), is still a loss. The net value is what matters. And if that net is under your initial investment, you don't pay tithing. Case 3: if you lose one year below your initial investment and the next year grow some but not enough from your initial investment, then you still have a loss from you initial capital therefore there is not profit from that initial investment, therefore you don't pay tithing. For example, my start up capital was 10K, next year I loss 4K, then next following year gained 3K, still i have an overall loss of 1K, so you don't have to pay tithing. Case 4: let's say you gained 3K one year, you paid your tithing of those 3K, then your initial investment would be 13K (this is your new mark or initial investment because you already pay tithing). Everything start from 13K mark..if you make more than 13K pay tithing or if you loss less than 13K don't pay tithing. This loop is eternal. Pay when you exceed, don't pay if you didn't exceed your initial investment. Especially if you're day trader, you don't know if you have gained or loss after you sell (realized).
