1. If I make bitcoins by doing survey's and only use what I gain on ModafinilCat, am I liable to be taxed?
2. Is it possible that I'll go into bitcoin debt due to taxes?
3. I can't be taxed if I have a grand total of 0 bitcoins, can I?
4. Do I need to keep a fancy log or have a bitcoin tax calculator? (Considering I'll only be making purchases off ModafinilCat)
1. Depends if it is classified as trading (self-employed income) or a hobby. Essentially, the test is "are you seeking to make profit". If so, HMRC would see it as self-employed income and it's added to you other income for taxes. If you are occasionally filling in a survey and happen to make some profit, it's sounds like a hobby. If you are a serial-survey-filler and so making a tidy sum, you are doing it for profit.
2. Bitcoins aren't taxed, but any Bitcoin income is reported as income at a pound value. So if you earned 1 BTC and you report your earnings, it would be £288, for example, or the fair market value.
3. It's possible. If you earned 100 BTC and then spent them, you still earned 100 BTC that could be taxable income.
4. I would keep records anyway, just in case.