Why do I receive another tax bill on a previous year?

The RBG imposes over 99% of the tax bill in the course of the tax year. Some tax bills are sent at a later stage. We cannot send the tax bill until we have full information. We also check if we have sent all tax bills. Sometimes we see in such a check that we have to send an additional tax bill. It is unfortunate that you are confronted with this bill in arrears. However, the costs were incurred. The legislation offers the option of imposing the tax bill retro-actively.
Do you want to pay your tax bill in instalments? Check the payment in instalments page read more about it here.