Thanks so much Snoopy.

I'm embarrassed to admit I have written this out slightly wrong sorry - although I'm not sure that it makes a difference to the fundamental question which I think you've actually answered but I just need to confirm.

I am an investor like you not a trader, I get into enough trouble trying to invest I think I'd be broke if I attempted to trade. I do not have the personality for it and I think it is always best to accept ones limitations

In the case study I gave (using simpler figures for illustrative purposes)

The error I've made is in relation to FIF investment 2

On day 1 of the tax year I hold FIF Investment 2 with a cost price of $10,000 (5000 shares at $2 in company A)

Then I purchase an additional $5000 (5000 shares at $1 in company A)

This means my position at the end of period 2 is $37,000

Then in Period 3 I sell half the shares in company A so 5000 shares.

So my question is really when you sell those 5000 shares how do you calculate your cost price of FIF investment going forward. Is is the average price so the remaining shares are 5000 shares at $1.50 or is it treated as the 5000 shares you sold are the first 5000 you bought so the 5000 shares remaining would have a cost price of $1 a share so $5000 as if it was the latter as you say you would be on $49,000 if you bought a further 22,000 and not over the threshold but if it was the former (the average) then you would be on $51,500 and you would be.

What I'm essentially trying to work out is how to arrange my investments to stay under the threshold but the way this year is going I'd probably owe zero in tax under FIF so probably over-thinking it.

Anyway thanks again Snoopy for your really helpful detailed reply as it helped me to work through my own thinking.