This isn't quite right.
If you think you are going to be making any money regularly, you need to talk to a local tax office as soon as possible.
What you spend and sell is just turnover, its not a profit. Your profit is the difference. This is what you are taxed on. If you spend £10000 on bitcoins, and sell then for £15000, then you would pay taxes on £5000, at your income tax rate. If you were not gaining an income from anything else, not even benefits, then £5000 would be below any taxable income, and you would pay no tax.
But you still need to tell the tax man that you earnt it in the first place.
The only time the turnover becomes an issue is when it hits the VAT threshold which is around £100K ( not checked for a few years) then you MUST register with the customs for VAT as soon as you think it may happen.
Never, ever try and fool the customs. They have more power than anyone, and WILL make your life hell if they think you are taking the mickey.
I used to be a government funded business advisor up until 2011.
Where in law does it say "
you still need to tell the tax man that you earnt it in the first place." or similar to mean the same thing? Seriously, would be nice to have this pointed out in black and white.
The only time the turnover becomes an issue is when it hits the VAT threshold which is around £100K ( not checked for a few years) then you MUST register with the customs for VAT as soon as you think it may happen. I think it's 75k nowadays for an ltd, don't quote me on that though, been a few years also since I needed to look into such things in detail.
And yes, the term 'profit' isn't correct, hence why I used ' '. Using that term makes it easier to explain however in terms of paying tax. If you are depositing large amounts of cash into your bank account, then you are liable for tax when you hit the threshold (as you know).
it can look like the whole thing is profit from somewhere.If you had standard benefits (JSA) then you could still earn £5000 from btc and not need to declare. If you have any other income AND the £5000 coming in (or any other amount of btc into fiat) then this counts towards your tax thresholds. e.g. you have a part time job that earns you £4000 a year and you made £5000 on btc that you stuck into your bank, then your total is £9000, and yep, you pass the threshold, but you only pay tax on the amount over the threshold.
I should've explained that better.
The tax office would dearly like everyone to declare exactly how much they're getting, but as the law stands you don't need to unless you pass the threshold. But ye, as mentioned above, if I am incorrect then please point me in the direction of the law that states otherwise.
Most of that £5000 can go back out as expenditure though.
edit: Just to add, I believe the reason that HMRC doesn't require anyone to state earnings unless they pass the thresholds is because things would get a little silly if everyone who washed a car, or a house window, for every £10, or £50, everyone who was earning under 8k a year had to declare (even though they wouldn't get taxed). But ye, again, if it does say it in law, please point me in the right direction, ty.