On items purchased at auction in the UK and exported (to the US for example) there is no VAT due on the item.
HOWEVER there is VAT on the Buyers Premium and THAT VAT is NOT refundable even if the purchased item is exported.
I have bought lots of stuff at UK auctions over the past decades and this is the system in use. I don't know why one VAT should be different from the other, but that is the way it goes.
Gnomon, you're right on where VAT is/isn't payable.
The VAT situation is quite simple. VAT is not payable on
goods bought by a purchaser from outside the VAT area; however VAT is applicable to
services provided within the VAT area, wherever the buyer is based.
Selling the gun to you is a service, so VAT is payable on the auctioneer's premium, but not on the gun itself.
The basic principle is that you can export a physical item (therefore no VAT payable) but you can't export a service (therefore VAT is payable).
The seller can charge you for the administrative side of not paying VAT, and may decline to remove the VAT from a low value item.
You need to ascertain the seller's VAT policy (some sellers are helpful, some are a PITA) and do the math(s) before buying.
N.
