Once again on the obligations assumed by the signers of a “strong” comfort letter

In June 2011, Andrés and Ceferino sent a document to a credit institution with the following text:

“We are writing to you in relation to the loan operation for the amount of 3,150,000 euros, which was formalised on 26 July 2007 before the notary of Pamplona […], by CARTERA HUMAN SL, novated on 24 April 2009, and amended again on 14 June 2011, whose principal balance owed to date has been set at 1,770,117.69 euros.

We are aware that, for the granting of this loan, you have taken into account and will continue to take into account, as a determining factor, the relationship of Andrés and Ceferino, the undersigned, with the company CARTERA HUMAN SL.

Consequently, we undertake before you not to alter this relationship, and, in particular, not to dissociate ourselves from the aforementioned company, while the loan operation mentioned in the first paragraph exists, or, where appropriate, to propose the necessary guarantees, at your discretion, to replace our dissociation from the aforementioned company.

Likewise, Andrés and Ceferino jointly and severally undertake to make every financial, technical and commercial effort to ensure that the business development of Human Management System S.A. and CARTERA HUMAN S.L. is satisfactory. In particular, we undertake to provide CARTERA HUMAN S.L. with the necessary financial resources, including capital increases or profit-sharing loans, so that the company can comply in full and promptly with the risks assumed in the loan operation mentioned in the first paragraph, the contents and agreements of which we declare to be fully aware of.

This document shall remain in force until the loan operation described in the first paragraph has a debit balance, in terms of principal, equal to or less than 700,000 € (seven hundred thousand euros)”.

The creditor credit institution sued Andrés and Ceferino requesting that they be ordered to pay 1,770,117.69 euros plus the appropriate default interest. At first instance, the claim was dismissed in its entirety. However, the appeal was upheld in part by the Navarra Provincial Court (Third Chamber), considering, on the one hand, that the document in question was in the nature of a “strong” comfort letter and that the scope of the indemnity obligation referred to the full amount of the outstanding loan; and, on the other, that the assumed undertaking was not equivalent to a suretyship, so that the signers of the letter were not obliged to pay the agreed default interest (Judgment no. 635/2018 of 21 December [ECLI:ES:APNA:2018:1087]). Consequently, it ordered the two aforementioned defendants jointly and severally to pay the claimant 1,770,117.69 euros, plus interest in accordance with Article 576 LEC from the date of the first instance judgment.

The Supreme Court rejected the appeals on the grounds of a breach of rules and procedure, respectively, lodged by Andrés (Judgment no. 944/2025 of 16 June [ECLI:ES:TS:2025:2725]). In what is relevant to this paper, the Supreme Court noted:

(a) The problem raised was that of the legal characterisation of the comfort letter as “strong” or “weak”, depending on the binding force on its signers.

(b) According to the legal doctrine (Supreme Court Judgments 731/2014, of 26 December [ECLI:ES:TS:2014:5755]; 440/2015, of 28 July [ECLI:ES:TS:2015:4276] and 424/2016, of 27 June [ECLI:ES:TS:2016:3055]), the enforceability of the comfort letter is not “automatic”, but requires as follows: (i) a clear and unequivocal statement of intent regarding the binding undertaking that the signer assumes, which excludes statements that support mere recommendations or statements of mere satisfaction, with no real intention to create a genuine binding relationship (“weak” comfort letters); and (ii) in view of the receptive nature of the unilateral statement of intent, the comfort letter requires the signer’s undertaking to be accepted by the creditor (although this acceptance does not have to be express, but can be inferred from the causal or underlying relationship that justifies the issuance of the statement of intent in order to secure the intended financing).

(c) Following the same case law, the Supreme Court added that, in accordance with the conduct of asset transfers and the guarantee function derived from comfort letters in the granting of business financing, the signer assumes an obligation of result with the creditor, or future creditor, to secure the planned financing instruments or operations planned, in such a way that pecuniary indemnity is guaranteed.

(d) From this perspective, and with regards to this specific case, the Supreme Court understood that the signers of the letter expressly undertook to jointly and severally use all efforts, including financial efforts, for the satisfactory carrying out of the business activity of the “guaranteed” company and to provide it with the necessary means for it to comply “in full and promptly with the risks assumed in the loan operation” in question (the terms of which were fully known by the signers, according to their own statement). This precluded the conclusion reached by the Provincial Court in classifying the comfort letter as “strong” and consequently stating that the signers guaranteed the lender’s pecuniary indemnity from being characterised as illogical or arbitrary.