Hi Mrs C.
(I thought about you yesterday when, for the first time in several months, I cooked my pilchard bake!)
As far as I'm concerned, if HM Government owes me money, I'm going to take it! A month's tax refund for my car would be around �15, so that would pay for a few bottles of wine ;-)
There's no 'administration fee' but you don't get the 10% surcharge, applied to 6 month disks back. For example, if a full year's tax on a car is �180, a 6 month disk is priced at �90+10% = �99. If you claim one month of that back, you get one sixth of �90 (=�15), not one sixth of �99.
The application procedure is incredibly simple. Just get the form from the post office, fill it in (which only takes about a minute), staple the disk to it and post it. The refund cheque should arrive a week or two later.
Chris