Capital gains in provisional tax returns

Must capital gains from an investment portfolio be included in the Turnover amount for provisional tax returns 1 and 2?

Yes you have to include the capital gain to your turnover on your IRP6

Thank you for your reply. And if you had a capital loss for the 2016 tax return (ITR12), can you offset that against the capital gain for the provisional tax return 2017 period 2?

The capital loss would have been offset against your income in the 2016 tax period so you unfortunately can't account for it on the 2017 income again.