I just wanted to check with you lot on something thats never been a problem up until know. Since we were taken over by this other company, weve been pulling a lot of their trailers. Whilst checking around I have found 3 to have either no identity plate/mot disc on at all, or its been a month out of date. I have refused to take these trailers but I just wanted to check that their is know way that they can make me take one by saying things like, oh yeah mate it has been tested, its just not had the documentation replaced yet ! we have accesss to all the trailers through the internet with regards which trailers are due mot etc and according to the one that I refused to take, it was tested according to the info on the computer? any info more than welcome, thanks 
If they are UK trailers, they will need a plating certificate and disc. You will find out if you are stopped in a Vosa check as it is one of their favourite bits to look for. They and you also need to know what weights the trailer is designed for
I am not sure what penalties, if any the driver would receive. It would certainly be a matter for the Commissioners.
I would probably say you are correct to tell the company, they may be tested and waiting for paperwork to be fitted
Alternatively, just mark it down on your daily defect sheets. Cover your Arse, not theirs 
it’s just the same if you turn up for work and your tax disc is out of date on the unit,but the new one has not been received yet.yes it may be taxed etc,but you as a driver get done for failure to display,it’s the same with trl’s you need to ensure that the plate is there,if not then it don’t leave the depot.that’s how i work and i don’t care what the boss say’s.stick to what your 1st instinct say’s m8. 
The trailer should have both plating certificate and MOT disc. If they are not attached to trailer, put it on your fault report, take that to the Transport Office, and make them sign a statement that says vehicle is legal, and just awaiting documentation. You will cop a fine otherwise. 
cheers for the info guys
Be a bit careful regarding the Minisrty plate on trailers. This will not be issued until the first test, which may be upto 13 months after the trailer was manufactured or the date of retail sale. If in doubt look at the manufacturers plate on the trailer for the date of manufacture.
Usually the VOSA will not bother the driver with fail to display Plating certificate or Test disc, unless they are also the Operator, but you get to hang around the checksite until they’ve finished all the checks and paperwork, which can be quite a long time. Having an out of date disc usually means the man with the hammer spends longer trying to find something worthy of a ‘9.’
If the trailer is of an age where it requires to be tested, then the best course of action is to leave it in the yard if the disc/plate are missing/out of date.
Tax discs are a different matter; the offence is; ‘fail to display’ so you as the driver have an equal chance of being ‘done’ along with the Operator.