If you can't beat the STT, you join it, says Uncle Theta. STT is Securities Transaction Tax. But Uncle Theta has found a way to make it a profitable thing with options. Firstly, STT is a tax on transactions in the markets. In Uncle Theta's world of options, this is what it means: when you sell an option you pay 0.05% of it as STT. So if I sell an option for Rs. 100, I will pay 5 paise to the government as STT. If I buy an option, I don't pay anything. I only pay when I sell it.