The tax you pay on a profit generated by a term deposit is not classified as capital gains tax (CGT). CGT applies to an asset (or investment), such as real estate or shares, where you either make a capital gain or a capital loss.
Interest earned on a term deposit is considered income though, and would need to be included in your annual income tax return.
The interest can be declared in the year the investment matures, or for the financial year it was credited to your account.
This also applies if you roll over your investment into a new term; you are still required to declare the interest earned at the rollover date (whatever financial year that falls in).