Buying a car or bike.

There are two taxes for cars:

1.  Annual Tax - This is bought every year and the price is determined on the engine size of the vehicle.  Starting at less than a dollar for a small motorcycle, a Honda CRV is around $25pa, and then from 3 litre engines up starts from around $300pa and increases quickly based on size.  Annual tax can only be paid for a window of around 2 months, so if you buy a car without the annual tax paid you can be fined (seemingly repeatedly - although I'm not clear on the rules having not been in that situation) until you buy your tax disc the following year.

2. Import taxes - NGOs and Government can import cars under certain tax exemptions.  However, those vehicles become subject to tax when sold to anyone who does not qualify for the tax-exemption.  As far as I know, the import tax is anywhere from around 100-150% of the value that the government assesses for the vehicle .  If you purchase a vehicle on which import tax has not been paid you will be liable for that tax.  (This is based on information passed on to me from other people)

In most cases, I suspect when they advertise vehicles as without tax they are referring to Number 2, the import tax.

Cars should also possess a roadworthy certificate which I believe has to be renewed every 2 years.

Hope this helps.