It is foreign income which may not be subject to tax if you:
Note, the 183 days includes all calendar days i.e weekends, public holidays, annual leave etc
To calculate how much income is exempt, you need to apply the following formula:
(Working days outside of SA for the specific period / by the total work days for the period) x the remuneration received for the period.
For the above formula, it’s important to note that work days only refer to days where services are rendered, and therefore excludes weekends, public holidays or leave taken. Furthermore, the period refers to the full period during a year of assessment over which a taxpayer is required to render services outside of SA.
Assume the taxpayer has passed the 183/60 day test and earned R500,000 foreign income while working overseas.
Total working days outside of South Africa: 145 days
Total working days for the period: 160 days
Exempt income = 145/160 X R500,000 = R453,125.
For further clarification refer Foreign Employment blog.