It is not a tax. The buyer must withhold 3 percent of the agreed price and pay it to the tax office on modelo 211 within one month, as a payment on account of the seller’s capital gains tax. The actual tax is 19 percent of the gain, for everyone. If the 3 percent exceeds what is owed, the difference is refunded on a return filed from one month after completion and within the following three.
Where this comes from: Retencion del adquirente de un inmueble, AEAT sede electronica, read 2026-09-07; arts. 5 and 8 Orden EHA/3316/2010, BOE consolidated text, read 2026-09-07; Tipos de gravamen IRNR sin establecimiento permanente, AEAT sede electronica, read 2026-09-07.