Is a valuation (report) mandatory for a mortgage in Spain?

Yes. A mortgage with a Spanish bank always requires a valuation carried out by an independent party. If the valuation is lower than the purchase price, the bank will provide a mortgage based on this lower value. As a result, your financing may be lower than expected.

Note: it is advisable if you engage an independent appraiser yourself, to first check with the bank where you want to apply for a mortgage whether the appraiser is officially recognised as an independent party to avoid double charges.