My income tax prerequisites have always been met i.e. IRP5 received and tax deducted from salary, I've never actually submitted a return and I am unsure of whether its legally mandatory.

Although I now fall below the new threshold of R500k, a friend advised that I register for efiling to make sure I don't have any previous returns outstanding, from when I was earning above the previous R350k threshold - I am reluctant because I am unaware of the income tax law, the penalties, implications etc.

Should I let sleeping dogs lie or register for efiling and risk possible penalties (if any) for missing and/or not submitting past returns?

What are the possible implications for not submitting an income tax return?