There's a lot of missinformation out there when it comes to returning a written off motorcycle to the road. Part of the reason why, is that the rules for cars and motorcycles are different.
Unsurprisingly, motorbike forums and websites are full of half truths and hearsay, and unfortunately the gov.uk and VOSA websites don't offer much information. To set the record straight, we got in touch with VOSA for the definitive low-down. Here's what they had to say:
It is firstly important to note that write off categories are not immutable rules but rather the opinions of those assessors inspecting the vehicle. Therefore it is entirely possible for a category C write off from one provider could be a category B from another. Taken that into account to return a written off motorcycle to the road requires only that the vehicle be repaired to a road worthy standard.
Some insurance providers require a new MOT be conducted but this is purely their own company policy and not national law any pre-existing MOT remains valid regardless of a write off.
A scheme called the Vehicle Identity Check (VIC) operates in regard to written off cars where they have to have their identity confirmed after a write off. However this inspection does not apply to motorcycles and even for cars in non-statutory (i.e. the car can still be used if it has all the normal documentation regardless of the need for a VIC).
Just to reiterate, the only thing you need to do to return a category C, or D (or any) written off motorcycle to the road is repair it to a roadworthy standard. You do not need to re-MOT the bike, though some insurers might ask you to do it, and you certainly do not need a VIC check. You can read the original reply from VOSA can be found here.