Starting from July 2018, Spain has removed its minimum purchase amount for tax free shopping. Which means, you’re eligible for tax refund no matter how much you’ve spent! The minimum age for requesting a VAT refund in Spain is 16 and if your permanent residence is outside the EU, then you will be eligible for tax free shopping.
There are no particular exemptions for shopping tax free in Spain, but you should remember that this service applies only to goods which are physically exported from the EU and not to services such as train tickets, bus rides, restaurant or hotel bills.
Spain is implementing a new digital system for processing tax refunds named DIVA (Devolucion del IVA a viajeros en la Aduana) which will make the refund procedure smoother for the passenger. Waiting times at the customs will be reduced and requests will be handled more efficiently.