Banking Law and Powers of Attorney in Banking Transactions — Spain

1. Introduction

A power of attorney (poder) in Spanish banking allows one person, the principal (poderdante), to authorize another person, the attorney/representative (apoderado), to act on the principal's behalf in specified transactions.

In banking practice, a power may authorize the representative to:

• operate bank accounts;
• make transfers;
• withdraw or deposit money;
• obtain account information;
• sign financing documents;
• manage securities;
• create or cancel deposits;
• negotiate banking arrangements;
• in sufficiently specific cases, borrow money, provide guarantees or create security.

The central principle is:

The representative can bind the principal only within the authority actually granted.

Spanish banking disputes therefore frequently turn on the existence, scope, interpretation, termination and verification of representative authority.

2. Main Spanish Legal Framework

There is no single Spanish “Banking Power of Attorney Act.” The applicable framework comes principally from:

• Spanish Civil Code, especially the rules on mandate and representation;
• Commercial Code, where commercial agency/commission rules apply;
• Law 10/2014 on the organisation, supervision and solvency of credit institutions;
• Law 7/1998 on General Contracting Conditions;
• Royal Legislative Decree 1/2007 on consumer protection;
• Law 6/2020 regulating certain aspects of electronic trust services;
• eIDAS Regulation (EU) No 910/2014, as amended, for electronic identification/trust services;
• Law 5/2019 regulating real-estate credit contracts, where mortgage lending is involved;
• AML/CFT legislation, particularly Law 10/2010;
• payment-services legislation;
• Spanish notarial legislation.

The exact rules depend heavily on the transaction being undertaken.

3. Representation and Mandate Are Related but Distinct

Spanish law distinguishes between the underlying relationship and external authority.

Mandate — mandato

The principal instructs another person to perform an act or service.

Power of attorney — poder

The representative receives authority to act externally in the principal's name.

The concepts often coexist, but they should not automatically be treated as identical.

This distinction matters in banking because a bank usually needs to determine whether the person appearing before it possesses sufficient external authority to bind the account holder.

4. Civil Code Article 1259

A fundamental rule appears in Article 1259 of the Spanish Civil Code.

As a general principle, nobody can contract in another person's name without authorization or legal representation.

An unauthorized transaction can potentially be ratified by the person on whose behalf it was purportedly concluded.

This is central to banking.

Suppose:

A owns an account

↓

B signs a loan in A's name

↓

B has no authority to borrow.

The bank cannot simply assume that A is bound merely because B held some unrelated authority.

5. Article 1713 — General and Special Mandates

Article 1713 is particularly important.

A mandate expressed in general terms covers acts of administration.

For acts going beyond ordinary administration, express authority is generally required.

This becomes critical for transactions such as:

• selling property;
• mortgaging property;
• borrowing;
• giving guarantees;
• compromising claims;
• disposing of substantial assets.

Therefore:

A power allowing someone to “manage my affairs” should not automatically be interpreted as authority to mortgage valuable property or guarantee another person's debts.

6. General Banking Power

A broadly drafted banking power may authorize operations such as:

• deposits;
• withdrawals;
• transfers;
• account administration;
• receipt of bank statements;
• routine payment instructions.

But the exact document must always be examined.

Terms such as:

“operate all bank accounts”

do not necessarily answer whether the representative may also:

“borrow €500,000 and mortgage the principal's house.”

The latter transaction may require much clearer authority.

7. Special Power of Attorney

A special power can authorize a particular transaction.

For example:

“The attorney is authorized to obtain financing from Bank X up to €250,000 and create a mortgage over Property Y.”

This substantially reduces uncertainty concerning the representative's authority.

Special powers are especially important for high-risk transactions.

8. Banking Transactions Requiring Careful Authority Review

Banks should exercise particular caution where an attorney seeks to:

• borrow substantial amounts;
• mortgage property;
• pledge securities;
• guarantee third-party debt;
• sell financial assets;
• close accounts;
• transfer large sums;
• alter account ownership;
• make gifts;
• transfer money to the attorney personally.

These transactions create greater risks of abuse or exceeding authority.

9. Bank's Duty to Verify Authority

A bank presented with a power of attorney should verify matters such as:

• identity of the attorney;
• identity of the principal;
• authenticity of the document;
• scope of authority;
• limitations;
• whether joint action is required;
• whether the power remains effective;
• AML/KYC implications.

For notarial powers, banks commonly examine the authorised copy and relevant notarial information.

10. Notarial Powers

Important banking transactions frequently use a notarial power of attorney.

A Spanish notary verifies matters including:

• identity;
• capacity;
• declaration granting authority;
• formal execution.

The notarial instrument then provides strong documentary evidence of the authority granted.

For transactions involving real property and mortgages, notarial form becomes particularly significant.

11. Mortgage Transactions

Consider:

Principal owns apartment

↓

Attorney approaches bank

↓

Attorney seeks mortgage loan secured by apartment.

The bank should determine whether the power expressly and sufficiently authorizes:

• borrowing;
• mortgage creation;
• identification or class of property where necessary;
• execution of notarial instruments.

Authority to operate a current account is not automatically equivalent to authority to mortgage real estate.

12. Spanish Supreme Court — Special Authority for Acts of Rigorous Ownership

Spanish Supreme Court jurisprudence has traditionally distinguished ordinary administrative acts from acts of disposition or rigorous ownership (actos de riguroso dominio).

Transactions such as disposal or encumbrance of important property generally require sufficiently explicit authority.

Banking significance

Banks should not stretch vague wording in a general power to justify:

• mortgages;
• substantial guarantees;
• disposals of assets.

The representative's authority must correspond to the legal importance of the transaction.

13. Supreme Court Judgment 642/2019, 27 November 2019

This Spanish Supreme Court judgment is particularly useful in understanding the interpretation of powers authorising acts of disposition.

The Court considered the relationship between a broadly drafted power and the representative's exercise of authority.

An important distinction emerges between:

1. whether the power objectively authorizes the type of transaction, and
2. whether the representative abuses that authority in the internal relationship with the principal.

Banking relevance

A bank should distinguish:

lack/excess of authority

from

abuse of an authority that formally exists.

They can have different legal consequences.

14. Abuse of Power

Suppose a parent gives an adult relative broad authority to manage assets.

The attorney then transfers substantial funds to themselves.

Two separate questions arise:

External authority

Did the power legally authorize the transaction?

Internal abuse

Did the attorney violate duties owed to the principal?

A transaction can therefore raise abuse questions even where the document appears broad.

Banks should pay particular attention to obvious conflicts of interest.

15. Self-Dealing — Autocontratación

Self-dealing occurs where the representative effectively acts on both sides of a transaction or benefits personally from the authority.

Example:

Principal

↓

Attorney

↓

transfers principal's money

↓

Attorney's own account.

Spanish jurisprudence treats conflicts of interest and self-contracting carefully.

Express authorization can be particularly important where self-dealing is contemplated.

16. Conflict of Interest

Banks should identify situations where the attorney's interests conflict with those of the principal.

Examples:

• attorney guarantees their own company using the principal's property;
• attorney transfers principal's funds to themselves;
• attorney mortgages principal's house to secure attorney's debt.

The presence of formal authority should not automatically cause obvious conflict indicators to be ignored.

17. Power to Borrow

A power to administer property does not necessarily include unlimited power to borrow.

If an attorney seeks credit in the principal's name, the bank should examine whether the instrument authorizes:

• borrowing;
• credit facilities;
• loan contracts;
• relevant maximum amounts, if specified;
• related security.

This becomes even more important where the financing primarily benefits the attorney or a third party.

18. Power to Guarantee

Guaranteeing another person's debt can create a major contingent liability.

Suppose:

Company owes Bank €1 million

and an attorney signs:

Principal guarantees Company's debt.

The bank should verify that the attorney possesses sufficient authority to create the guarantee.

Routine account-management authority should not simply be assumed to include authority to expose the principal to substantial third-party liabilities.

19. Power to Pledge Financial Assets

A customer may own:

• shares;
• investment funds;
• deposits;
• securities.

An attorney might seek to pledge these assets as security.

The bank should examine:

• authority to dispose or encumber;
• description/scope of assets;
• transaction limitations;
• conflict-of-interest issues.

The distinction between managing investments and pledging them for debt can be legally significant.

20. Joint Attorneys

A principal may appoint several attorneys.

The power may require them to act:

Jointly — mancomunadamente

For example:

Attorney A + Attorney B must both sign.

Separately — solidariamente/indistintamente, depending on drafting

Either attorney can perform authorized acts independently.

A bank must follow the actual representation structure.

Allowing one attorney to act where two signatures are required can expose the bank to liability.

21. Corporate Powers

Companies frequently act through:

• directors;
• board-authorized representatives;
• commercial attorneys;
• special attorneys.

A bank dealing with a Spanish company should verify:

• corporate identity;
• current directors;
• registered powers;
• limitations;
• revocations;
• signing rules.

The Commercial Registry (Registro Mercantil) therefore plays an important role.

22. Corporate Banking Example

Suppose a company's registered rules require:

Director A and Director B jointly for borrowing above €1 million.

Director A alone seeks a €3 million loan.

Even if A can perform routine banking operations, the bank should not assume that A alone can bind the company to the larger facility.

Authority must be verified against the applicable corporate and registered representation structure.

23. Revocation

Under Spanish mandate principles, powers can generally be revoked subject to the applicable legal framework and circumstances.

Once properly revoked, the attorney should cease using the authority.

For banks, an important practical question becomes:

When did the bank know, or when should the relevant revocation have become effective against it?

Banks therefore need systems for updating representation records promptly.

24. Death of the Principal

As a general rule under the Civil Code's mandate provisions, death can terminate the mandate, subject to statutory exceptions and the protection of certain acts performed without knowledge of termination.

The bank therefore needs procedures for situations where:

• the customer dies;
• the attorney continues presenting instructions;
• the bank learns of the death.

Once reliable notice exists, continuing to process transactions solely under an expired authority can create significant legal risk.

25. Article 1738 of the Civil Code

Article 1738 is especially important for third parties.

Broadly, transactions carried out by an attorney who was unaware that the mandate had ended may, subject to the statutory requirements, remain effective against third parties acting in good faith.

The rule protects transactional security.

Banking significance

The timing of:

• termination;
• knowledge;
• notification;
• third-party good faith

can determine the legal effect of a transaction.

26. Incapacity and Support Measures

Spanish disability law was substantially reformed by Law 8/2021.

The modern framework emphasizes support for persons exercising legal capacity rather than the older model of broad judicial incapacitation.

This has significant implications for banking.

Banks may encounter:

• preventive powers;
• support measures;
• guardianship-type judicial arrangements where legally applicable;
• powers intended to continue in anticipation of future support needs.

The bank must examine the specific legal instrument rather than assuming that disability automatically removes legal capacity.

27. Preventive Powers

Spanish law permits planning for circumstances in which a person may later require support.

A properly structured preventive power can therefore be extremely relevant to banking arrangements involving:

• older customers;
• long-term asset management;
• investment management;
• payment of expenses.

The scope and continuing effectiveness depend on the instrument and applicable Civil Code provisions.

28. AML and KYC

A power of attorney does not eliminate AML obligations.

Under Law 10/2010 on prevention of money laundering and terrorist financing, a bank must identify relevant persons and understand the relationship and transaction where required.

The bank may therefore need information concerning:

Principal

Attorney

Beneficial owner

purpose/nature of transaction.

29. Suspicious Transactions

Consider:

• elderly principal;
• newly appointed attorney;
• historically small account activity;
• sudden €200,000 transfer;
• destination is attorney's personal company.

Even if a document appears formally valid, the transaction may require enhanced scrutiny under:

• fraud controls;
• AML monitoring;
• internal safeguarding procedures.

A power of attorney is authority, not immunity from regulatory controls.

30. Data Protection and Banking Secrecy

An authorized attorney may be entitled to receive banking information within the scope of authority.

But the bank should not disclose information outside that scope.

For example:

authority to make a single payment

does not necessarily mean:

unlimited access to every historical financial record.

GDPR and Spanish data-protection law can therefore interact with representation rules.

31. Online Banking

Powers of attorney now interact with digital banking.

Questions include:

• Can the attorney receive their own credentials?
• Can the attorney initiate online transfers?
• What limits apply?
• Can the attorney use electronic signatures?
• How does the bank authenticate representative capacity?

The bank should ideally issue representative-specific access rather than encouraging attorneys to use the principal's personal credentials.

This preserves a better audit trail.

32. Electronic Signatures

Under the eIDAS framework and Spanish electronic-signature legislation, electronic signatures can have legal effect.

But two questions must be separated:

Authentication

Was Attorney A the person who electronically signed?

Authority

Did Attorney A have power to sign this transaction for Principal B?

A technically valid electronic signature does not automatically prove adequate representative authority.

33. Unauthorized Electronic Transaction

Suppose an attorney has authority to make payments up to €10,000.

The attorney initiates a €100,000 transfer.

The system correctly authenticates the attorney.

Yet authentication does not resolve the representation issue.

The transaction may still exceed the attorney's legal authority.

Therefore:

identity verification and authority verification are separate banking controls.

34. Ratification

Under Spanish civil-law principles, an unauthorized transaction may potentially be ratified by the principal.

Example:

Attorney without adequate authority signs financing.

Principal subsequently:

• expressly confirms it; or
• engages in conduct capable, under applicable law, of amounting to ratification.

Ratification can therefore cure certain representation defects, but banks should not rely on assumed ratification when proper authority can be obtained beforehand.

35. Apparent Authority

Spanish law does not simply permit banks to rely on every appearance of authority.

Protection of third parties depends on the applicable legal doctrine, the facts and good faith.

Where a bank has clear evidence that authority is limited, it cannot safely ignore those limitations merely because the representative appears trustworthy.

36. Consumer Protection

Where an attorney enters a consumer banking transaction on behalf of a principal, EU and Spanish consumer rules can still apply where the principal qualifies as a consumer.

Important CJEU cases include:

Banco Español de Crédito, C-618/10 (2012)

Established strong judicial control over unfair consumer terms.

Aziz v Caixa d'Estalvis de Catalunya, C-415/11 (2013)

Strengthened effective protection against unfair mortgage terms.

Banco Primus, C-421/14 (2017)

Further addressed unfair terms in Spanish mortgage enforcement.

Gómez del Moral Guasch v Bankia, C-125/18 (2020)

Addressed transparency in Spanish mortgage terms.

These cases do not primarily concern powers of attorney, but they remain relevant where an attorney signs a consumer banking contract for the principal.

37. Mortgage Transparency

Where a representative participates in a mortgage transaction covered by Law 5/2019, the bank must still consider applicable:

• pre-contractual information;
• transparency requirements;
• notarial procedures;
• consumer protections.

Using an attorney does not automatically eliminate mandatory borrower protections.

The exact procedure depends on the nature of the representation and transaction.

38. Foreign Powers of Attorney

Spanish banks frequently encounter powers executed abroad.

Questions can include:

• authenticity;
• apostille or legalization;
• sworn translation;
• equivalence of foreign notarial functions;
• scope of authority;
• compliance with Spanish formal requirements.

For certain public-document transactions, the bank/notary may require proof that the foreign instrument is legally sufficient for the contemplated Spanish transaction.

39. Hague Apostille

Where the relevant states participate in the 1961 Hague Apostille Convention, an apostille can simplify authentication of qualifying foreign public documents.

But:

Apostille proves authentication of the public document; it does not expand the authority contained in it.

A perfectly apostilled power can still be inadequate for a mortgage if it does not grant mortgage authority.

40. Bank Liability for Ignoring Restrictions

Suppose a power states:

Attorney may transfer a maximum of €20,000 per transaction.

The bank executes:

€300,000 transfer.

If the attorney lacked authority for that transaction, the bank may face significant contractual and civil-liability issues.

Banks therefore need systems capable of recording meaningful restrictions rather than merely noting:

“POA exists.”

41. Bank Liability for Wrongfully Rejecting a Valid Power

The opposite problem can also arise.

A bank might refuse a transaction despite a legally valid and sufficiently broad power.

Depending on the circumstances, unreasonable refusal could interfere with the principal's contractual banking rights.

Banks therefore need a balanced approach:

verify carefully — but do not invent restrictions that the law or document does not impose.

42. Spanish Supreme Court Case-Law Principles

Spanish Supreme Court jurisprudence on representation supports several recurring principles relevant to banking:

1. the representative must act within the authority granted;
2. general administrative authority should be distinguished from powers of disposition;
3. the wording and purpose of the power matter;
4. exceeding authority differs from abusing authority that formally exists;
5. self-dealing/conflicts require particular scrutiny;
6. ratification can be relevant to unauthorized acts;
7. third-party good faith can matter in determining external effects.

STS 642/2019, 27 November 2019 is particularly useful when analysing broad powers and acts of disposition.

43. Relevant Case-Law Table

The CJEU authorities above are consumer-banking cases rather than direct POA cases. Their relevance is complementary.

44. Practical Bank Verification Model

Before accepting a transaction through an attorney, a Spanish bank can conceptually apply:

Step 1 — Identify

Who is the principal?

Step 2 — Authenticate

Is the power genuine?

Step 3 — Identify representative

Who is acting?

Step 4 — Scope

Does the document authorize this specific category of transaction?

Step 5 — Restrictions

Are there limits on amounts, assets or counterparties?

Step 6 — Validity

Has the power been revoked or otherwise terminated?

Step 7 — Conflict

Does the attorney personally benefit?

Step 8 — Compliance

Are AML, sanctions, fraud and consumer rules satisfied?

Step 9 — Formalities

Does the contemplated transaction require notarial or registry formalities?

Step 10 — Evidence

Can the bank demonstrate why it accepted the attorney's authority?

45. Example: Valid Routine Transaction

Maria grants Carlos a notarial power authorizing him to:

• operate account X;
• withdraw funds;
• make transfers up to €20,000.

Carlos orders a €5,000 payment to Maria's electricity contractor.

The transaction falls naturally within the described authority, assuming the power remains valid and other banking controls are satisfied.

46. Example: Questionable Mortgage

The same power merely states:

“manage Maria's bank accounts.”

Carlos attempts to:

• borrow €600,000;
• mortgage Maria's house;
• use proceeds for Carlos's company.

This creates multiple problems:

• borrowing authority;
• mortgage authority;
• act of disposition;
• self-interest/conflict;
• consumer/mortgage formalities.

A bank should not equate routine account management with authority for such a transaction.

47. Example: Corporate Guarantee

Company A appoints its CFO to:

operate bank accounts and make ordinary payments.

The CFO then attempts to guarantee €5 million of Company B's debt.

The bank should investigate whether the representative possesses authority to provide guarantees.

The transaction is qualitatively different from ordinary account operations.

48. Main Legal Risks

For Spanish banks, POA transactions create several categories of risk:

Authority risk

Representative exceeds the power.

Fraud risk

Power is forged or manipulated.

Conflict risk

Attorney benefits personally.

Revocation risk

Bank acts on a terminated power.

AML risk

Representation disguises the beneficial participant.

Operational risk

Bank's systems fail to record restrictions.

Consumer risk

Representative is used to circumvent mandatory protections.

Litigation risk

Principal later disputes the transaction.

49. Core Legal Principles

The Spanish framework can be reduced to several rules:

First: A bank must distinguish the attorney's identity from the attorney's authority.

Second: General administrative authority does not automatically include every act of disposition.

Third: Mortgages, guarantees, substantial borrowing and similar transactions require particularly careful authority analysis.

Fourth: A valid power does not eliminate AML, fraud, consumer or transparency obligations.

Fifth: The bank must consider revocation and other grounds terminating authority.

Sixth: Self-dealing and conflicts of interest require heightened attention.

Seventh: Digital authentication does not cure a lack of legal authority.

50. Conclusion

Powers of attorney are an essential part of Spanish banking practice, but they do not give representatives unlimited control over a customer's financial affairs.

The core legal framework comes primarily from the Spanish Civil Code—particularly Articles 1259, 1713 and the rules governing termination of mandate—together with notarial, corporate, AML, consumer, mortgage and electronic-transaction rules.

Spanish jurisprudence distinguishes carefully between:

having authority → exceeding authority → abusing existing authority.

That distinction is especially important after STS 642/2019 of 27 November 2019 and the broader Supreme Court jurisprudence concerning acts of disposition, conflicts of interest and self-dealing.

For banks, the safest legal model is therefore:

authenticate the power → identify the attorney → determine its precise scope → check limitations and continued validity → examine conflicts → apply AML/consumer controls → document the decision.

In high-value transactions—particularly mortgages, guarantees, pledges, borrowing and transfers benefiting the attorney—the existence of a general banking power should never automatically be treated as sufficient authority.