Yes, you must display a current tax disc.
If bought in advance, it does not come into effect until the 1st day of the following month and should not be displayed before then.
I have never understood why this is, since a renewed disc starts on the first day of the next month and not the current month. Therefore, if I have purchased an April disc, I must have had one that runs out this month surely?
TCL - it is possible to have a gap between an expired VEL and the next one, such as when the vehicle is kept off the road. SORN was introduced to keep tabs on this.
You can have a gap between expired discs but what we're talking about is renewal discs. If ma last disc ran out in January and I bought one to-day, it would cover me from March 1st, If it runs out at the end of March it will start 1st April. Does the same not apply to SORNs?
You mentioned renewal discs, the question just says "new".
You can apply for a new VEL, e.g. where a break exists, two working days before the licence is due to start. Thus I could buy my new tax disc for April on 29th March and would gain 3 free days.
The dvla website clearly states that if you buy a tax disc in advance of the first day of the month, it is not valid and should not be displayed UNTIL the first day of the month.
Why would you want to display a disk that isn't in force yet?
There's a simple solution - when you are in receipt of your new tax disk - put a reminder on your phone to go off that morning to change the disk from the old to the new disk - therefore avoiding all of the confusion.
I said renewal because bluebabe said she/he "has cover to date." It was my understanding that unless it was a renewal disc, a disc was backdated to the beginning of the month. Checking the DVLA site , it does say a disc cannot be bought more than two days in advance of it starting if there's more than a month's break. If it can't be dispalyed until it starts, why is that then?