CGT is a tax you pay on the profits you make on the disposal (sale) of your assets.
Are you a provisional taxpayer? Here' to deal with CGT
If you're a provisional taxpayer and you estimate your taxable income for the first, second and third provisional tax periods, you must take your capital gain for the year into account. Unless, of course, you're entitled to base your estimate on the 'basic amount' (i.e. last year's taxable income).
You must also exclude any taxable capital gain from the basic amount for an earlier year of assessment because the taxable capital gain is usually irregular.
As long as you rely on the basic amount (the amount appearing on the IRP 6 provisional return issued by SARS) appearing on the first and second provisional period returns. You won't incur any penalties and interest, provided of course you pay the amount due on time.
As a provisional taxpayer, the onus is on you to declare all your gains and losses. You need to calculate your due taxes correctly and pay SARS on time.
PS. We recommend you check out: Provisional Tax 101. It gives you the step-by-step advice you need to estimate, calculate and pay over your provisional tax correctly - yourself!