New builds: IGIC and stamp duty
Buying a new home from a developer is taxed under IGIC at the general 7% rate, with reduced rates in certain primary-residence cases, plus stamp duty (AJD) on the notarial deed.
Resale homes: property transfer tax
A resale home is taxed under the regional Property Transfer Tax, with reduced rates for young buyers, large families and people with disabilities when the primary-residence requirements are met.
Other costs worth budgeting for
Notary, land registry, a gestoría (administrative agent), a valuation if there is a mortgage, and the municipal capital gains levy, which is owed by the seller unless otherwise agreed. It pays to work all of this out before signing the deposit contract, not after.