The easiest way is to request it from SARS. The good news is that SARS won’t provide your tax number to another person, so you can request it telephonically by calling the SARS Contact Centre on 0800 00 72 77. Make sure that you have your ID number on hand.
If you are registered on eFiling, you can just log on and check your SARS tax number.
You can also look at your IRP5 form or you can ask your employer. Another option is by enquiring with your employer’s accountants.
Your SARS tax number can also reflect on your payslip. You could also check on previous tax returns.
If none of these options work, your best bet will be to visit a SARS branch and request it from the SARS consultants.