SARS has issued a statement on their website that all money due to them are to be paid before 29 March 2019. Read statement here.
After the deadline, they are going to start taking action against tax payers with money due. This includes raising interest on outstanding amounts. SARS also has the right according to law to take money from a taxpayers bank account for money owed to them.
It is important to make arrangements with SARS to pay outstanding taxes in installments. If you owe tax due to incorrect assessments or input VAT not allowed, you have to submit disputes in order to correct this.