It seems that the Doctor’s incorporated practice may qualify as a SBC as defined.
However bear in the mind following:
The R20million pa. requirement relates to “gross income”(as defined in the IT Act) and not mere turnover.
Only Shareholder : Must be a shareholder throughout the tax year.
Owns no other shares: He must not any own other shares at any time during the tax year.
Investment Income: Ensure that you are aware of the definition of investment income as defined under Section 12E (4) (c) of the Act since income such as royalties, annuities etc are included. Furthermore the 20% relates to the total receipts and accruals(excluding capital receipts) plus all capital gains.
Personal Services and Personal Service Provider : see number of employees below.
Where the company employs at least 3 fulltime employees in the practice who are not connected to him throughout the tax year then the personal services and personal service provider requirements will not apply to the company.
I also suggest you familiarize yourself with Interpretation Note 9 (issue 5)issued by SARS in this regard.