Main requirement:
Debt to Income Ratio
A mortgage application only makes sense if your DTI score (Debt to Income ratio) offers enough room. The banks in Spain require that a maximum of 35% of the net income may be used for all fixed costs, such as gross housing costs, loans and spousal maintenance throughout Europe combined.
Please note: the Debt-to-Income ratio is only one of the factors taken into account, but it is an important factor to comply with.