Hi all, I'm new to trading and have what's probably a basic...

Hi all, I'm new to trading and have what's probably a basic question.

I'll start from the start:

I bought shares in KGN @ $1.54, then doubled the amount of money invested at $2.16 and then doubled my total amount invested at $3.45.

Hypothetically, let's say I invested $2.5k at $1.54, then $5k at $2.16 and $15k at $3.45.

My total portfolio now has an average buy price of ~$2.80 for KGN shares.

By doubling down at $3.45, I'm now starting to lose significant money as the share price is dropping (currently @ $3.33).

However despite this drop and re-buy, my portfolio is still showing a 20% profit. I believe the share price will continue dropping for a bit, so ideally I'd like to sell the $15k worth invested at $3.45 and re-buy at a lower price. However, if I sold $15k worth, do I pay and capital gains tax on that? Technically I've lost money on that portion, however I'm up money overall if I were to sell all shares at that share price. If I have to pay capital gains tax it's not worth me selling anything since it greatly affects the buy back price I'd require just to break even, let alone make profit.

So is there someone that can explain the capital gains tax system to me? Or a link? I haven't found any good info anywhere.

Hypothetically another scenario: if I bought 10k of shares at $1 and they are now worth $2 and I sell half to get my original investment out, do I pay tax on that original investment money considering I haven't actually pulled out profits yet per say (depending how you look at it)? Or is 50% of the money pulled out deemed as profit since is it calculated purely based on share price bought at and share price sold at for each scenario?

Thanks everyone!