What is the tax definition of carrying on a business.

I have been unemployed for the 2014 / 2015 tax year. For income, I have been getting casual work here and there. By casual I mean I worked on some events, did some technical drawings for a company and then helped with a school magazine. I was paid for all these jobs, for which I had to invoice and naturally I incurred expenses to do these jobs. Two events were overseas. There were a few months when I had no work at all. (My taxable income is less that the R70700 threshold. ) My question is, does this constitute as running a business in terms of provisional tax? (My taxable income is less that the R70700 threshold. )

No it will not if you fall below the tax threshold, however you should still file a tax return to be compliant with SARS and up to date.