Why do some airports demand a VAT number to sell you avgas?

gallois wrote:

Exactly how you reclaim and who from I don’t know I just remember a news article about how many Brits don’t know about this and how much is never reclaimed.

It might be VAT refund for visitors to EU? Summarised:

1. Ask if the shop follows this scheme
2. Show proof of non-EU residency
3. Complete reclaim form
4. Get form and invoice stamped by customs when exiting the EU
5. Send off form for reclaim

Payment may be on the spot in the airport, through an intermediary agent, or direct from the shop, and is probably subject to a commission or handling charge. I think it’s aimed at luxury goods, e.g. Louis Vuitton, so of little use to GA.