I don't quite understand that . The situation here is that to be able to tax your car, you need both an MOT and Insurance. You can get your tax online as the DVLA which issues your tax has a database of your details as it is a requirement that both the garage that does your MOT and your Insurance company to enter all the information online. The only exception or caveat to this is that your MOT must not expire the same month as you apply for your tax. For example if your MOT expires on the 20th February you cannot tax your car on the 1st February. However you can have your car MOT'd early, so if you had it done on the 31st January you can tax it and the MOT would not expire until the 20th February the next year. That also applies to insurance I think. This rule has applied for a few years now, at one time you could go to The Post Office and tax your car even if the insurance and MOT expired the next day. No records were kept by the Post Office staff, they simply glanced at the relevant certificates and if they were current they just issued a tax disc. It was fairly common for people to go long periods without an MOT as back then it was a fairly minor offence.
Sorry I should have expanded that. In Kiwiland in order to get your Warrant of Fitness (ie suitable to be driven on public roads), you must have the registered/taxed. Car insurance, believe it or not is not a legal requirement here, which is very unfortunate if you get hit by uninsured dunce. Having said that larger majority are indeed insured. Incidentally both WOF and registration systems here interface, way to catch more out. You can legally drive un WOF'd to get a new WOF, "if" you have booked in.
Anyway, I'm just confusing you guys now. But I find it very interesting the differences.