Only the offside needs to be working to pass the MOT.

8 minutes ago, M18ntt said:

Sorry if this is a silly question but if rear fog lamp bulbs are fitted to each side why are they both not activated? Seems daft to me. My Octavia is up for its first MOT tomorrow and I've been dashing around this afternoon trying to get a replacement because I thought my near side fog had blown. 

 

I thought the same, but as others have said, only need the offside to work in the UK for the MOT to be passed. (my car had it's first MOT under my ownership on Monday, and passed with just the one)

 

I guess with the mass production it's easier to install both bulbs then just code the required one for each region.