As the reader will not have gone unnoticed, on October 18, 2018, Judgment 1505/2018 of the 3rd Chamber of the Supreme Court, dated October 16, was published, declaring – with two particular votes, one concurrent and the other dissident – that the taxpayer of the Stamp Duty Tax must be the lender, and not the borrower, mainly because the greatest interest in the mortgage guarantee is registered in the corresponding property registry (constitutive requirement) lies precisely on the financing bank entity. Although on the same date, the spokesman of CECA (Spanish Confederation of Savings Banks) argued that the issue was of a tax nature, and not civil-patrimonial, so the claims of the mortgage debtors should be made directly to the regional haciendas – what seems to us legally dubious. However, one day later, the president of the 3rd Chamber announced his intention to convene a plenary session that decides the following (by order) pending appeal on the same matter, in order to confirm or modify this jurisprudential line. In any case, Sentence 1505/2018 would be definitive and binding, and only an ordinary remedy of amparo before the Constitutional Court would be against it, of uncertain prognosis, since the right to legal security is contained in Article 9 of the Constitution, and it does not result in a right or freedom from those included in articles 14 to 29.