Stocks and shares ISA tax rules

Not, none of it is subject to income tax.

The tax man says, I have a few basic rules:

1) don't put more than £x amount of money into an ISA in one tax year.

2) don't contribute to more than one ISA of the same type in the same tax year otherwise it would be more of a pain to check you haven't broken rule number 1.

3) if it's an S&S ISA where you can choose what type of investment to hold, your ISA manager should make sure the type of investments you buy are in the approved categories of investments that can be held in an ISA and if not or if their statuses change (like if a listed company you're holding goes private you can't keep it even if you don't want to sell up)

Stick to the rules and all the income (interest, dividends, property income distributions, and all the capital gains you make, are all free of UK tax. Keep it in the ISA or take it out of the ISA, the tax man doesn't care.

And the original £10k you put in, you can have it back whenever you want - taxman doesn't care about that either. That £10k is your money and presumably you paid whatever appropriate amount of tax when you first got it (e.g. earned it from an employer, received it as profits on some other type of investment in the past, etc).

If you stick £10k in an ISA and then through smart investing or good fortune turn it into £10 million, you can take that all out with no tax to pay.