It is after 7 years, every year in order to get tax disc.
The check usually consists of checking the VIN number, kicking the tyres, looking for smoke, or even a probe up the pipe?, sound the horn, drive round and see the brakes work..that's it.
I have a four year old TM30, which I did myself using the Mrs'ID and house book. Been away many times, both hotels in Thailand and trips to Dubai/UK. Done retirement extensions no problem, in fact, last time the IO printed out a new TM30 as mine was getting tatty.