Buying property in Madrid is exciting, but mistakes can be costly. This guide highlights the most common errors buyers make: skipping legal checks, underestimating renovation costs, ignoring community fees, not verifying property debts, and making offers without understanding market pricing. Foreign buyers may also struggle with paperwork like obtaining an NIE or opening a Spanish bank account. Another major mistake is focusing only on the apartment interior and ignoring the building condition (roof, façade, elevator, community financial health). We explain how to protect yourself with a checklist approach, including reviewing the nota simple, confirming property registration details, and making a realistic total-cost budget. With the right preparation, you can buy confidently and avoid expensive surprises.