ITP runs from 4% to 10%, depending only on the comunidad
Impuesto de transmisiones patrimoniales is set by each comunidad autónoma, and the range is the widest of any country here: 4% in País Vasco, 6% in Madrid, 10% in Cataluña. On a 230,000 flat that is a difference of nearly 14,000 euros for the same purchase, decided entirely by which side of a regional border the property sits.
Pick the comunidad above before you read the cash-to-complete figure. Left unset, the calculator uses an 8% national placeholder, which is close to nobody's rate.
Reduced rates for young buyers, large families and social housing exist in most comunidades and are not modelled, so treat the figure as the general rate for someone with no entitlement. A few regions, Cataluña among them, apply a banded scale above high values; that is simplified to the general rate here.
A new-build is a different tax altogether
Second-hand homes pay ITP. A new home bought from the developer pays 10% VAT plus actos jurídicos documentados instead, typically another 0.5% to 1.5%. The two regimes are not variations of each other, and this calculator models the second-hand one, so a new-build completion will cost more than it shows.
No mortgage insurance, and the valuation sets the loan
Spain has no mortgage insurance. Lenders normally finance 80% of the lower of the price and the bank's own valuation, which is the trap for a buyer who has agreed above the tasación: the shortfall comes out of your deposit, not the loan. Home insurance assigned to the mortgage is a standard condition.
IBI is a municipal rate on the cadastral value, which sits well below market price, so the 0.5% of price used here is an equivalent rather than the rate on your recibo.