Ground clause or floor clause, in relation to the mortgage loan and the purchase of a home, through a variable interest mortgage, is the name of a contractual clause that establishes a minimum limit on the interest that will be applied to the installment even if the interest rate decreases. It is a clause that benefits the banking entity and harms the individual who has requested the loan since when interest rates drop or become negative, the clause prevents it from being reflected in the monthly installment. Depending on the regulations of the country, the conditions of the contract and its transparency and clarity, it may be considered a negative, illegal, or void clause, therefore it may be considered bank fraud.

In Spain, floor clauses are illegal. Their nullity and abusive nature were declared by a judgment of the Supreme Court on May 9, 2013, although it limited the refund of illegally collected amounts by banks from the date of the judgment.

However, the Court of Justice of the European Union ruled, in an unappealable judgment on December 21, 2016, against the limitation of the retroactivity of the nullity of floor clauses, so banks and savings banks are required to refund all money illegally collected by floor clauses since the signing of the mortgage for the acquisition of housing.