S W (Costa del Sol)
Your property is in Andalucia, so we should not speak of Spanish law but of Andalucian law, because each of Spain’s 17 Autonomous Regions has its own rules. Further, many of the Regions changed their rules in 2015 after the European Court of Justice ruled that the previous national law violated the equal rights of non-residents who are EU citizens. In your case, the Andalucian inheritance law applies. Your son and daughter, also EU citizens, each have an exemption of €175,000. If your property is valued at under €350,000, this means they will pay no tax at all. After Brexit, when your heirs are no longer EU citizens, they will face a tax bill of around €65,000 on a property worth €350,000.