The recent ruling of the Constitutional Court dated January 18, 2024, resolves the question of unconstitutionality raised by the Contentious-Administrative Chamber of the National Court, declaring the nullity, on the one hand, of Additional Provision 15 of Law 27 /2014 of the Corporate Tax (LIS, hereinafter) in relation to the limitation of the compensation of Negative Tax Bases (BINs) established for large companies, with a turnover greater than 20 million euros; as well as with respect to the restriction on deductions to avoid double taxation at 50% of the taxpayer's full amount.

On the other hand, the unconstitutionality and consequent nullity of section 3 of the 16th Transitional Provision of the same regulatory text referred to above is also decreed, corresponding to the obligation to integrate into the tax base, the impairments that have been deducted in previous years, at a rate of one fifth per year, for a period of 5 years from 1/1/2016, this integration being automatic, although the shares that generated the deductible impairment at the time will not have effectively recovered their value.

The reason on which the decision of the constitutional body is based is the improper use of Royal Decree Law 3/2016, pursuant to which the aforementioned modifications were added to the LIS, which substantially altered a matter reserved for the law. , in accordance with the limitation established in article 31.1 of our Constitution, such as the obligation to contribute to the support of public expenses, by widening the tax base of the Corporate Tax, thereby transgressing the material limits of the decree-law, established by article 86.1 of the Spanish Constitution

However, despite the above, the effects of the declaration of unconstitutionality and nullity were limited, in the ruling of the Constitutional Court itself, to the situations that were contested on the date of issuance of this ruling. In relation to this issue, the dissenting opinion of one of the judges expresses the opposite, in which he alludes to the injustice of limiting the effects of the ruling to the detriment of those taxpayers who complied with the rule and who did not challenge it, thus so that, indirectly, an attitude of belligerence is required on the part of taxpayers, in the sense that they have known that the rule was going to be declared unconstitutional and, therefore, have appealed it.