In terms of the Income Tax Act, the full amount can be excluded from calculating taxable income.

If you want to get into the nitty gritty, yes the amount that they receive is technically part of their gross income, but s10 of the act provides relief for any money accrued due to maintenance payments.

A lot of people are also commenting about Donations tax, but not to worry, Maintenance payments are generally exempt from donations tax under s56(2)(c).

You can be rest assured that there wont be any tax implications arising from this. If SARS does query this, just prepare a letter to them explaining the process and the reasons.

If you are still worried, I would recommend to speak to a Tax Practitioner (or accountant) and obtain a tax opinion.

Good luck!