This is the clause that Consumers Authorities propose regaridng VAT accruing in off plan purchases:
2.1. Price and VAT output
The seller will output to the buyer, which will be obliged to pay it, the full amount of the Added Value Tax (VAT) which taxes the advanced amounts and the delivery of the house. The output will be calculated on the full price.
Said output will be made as the tax accrues, that is, for advanced payments before the delivery of the house at the payment of every one of them and on the effectively received amounts. The part of the tax corresponding to the rest of taxable amount will be accrued and output once the house is delivered to the buyer, which is when the buyer makes the corresponding payment.