How to Plan Inheritances and Successions with Cryptocurrencies and Digital Assets in Spain

Succession planning in Spain has been profoundly transformed. Assets no longer consist solely of real estate, bank accounts and corporate shareholdings, but also cryptocurrencies, tokens, NFTs, positions in DeFi protocols and digital assets with real economic value. This new scenario presents legal, tax and technological challenges that require a professional and multidisciplinary approach.

The main problem is evident: each year the number of heirs who cannot access the deceased’s digital assets increases due to lack of private keys, documentation or recovery instructions. Lost wallets, blocked platforms or unknown investments generate irreversible asset losses. In parallel, the Tax Authority has strengthened crypto asset taxation through reporting obligations and specific forms.

In this context, proper planning is essential to ensure the effective and secure transmission of digital assets.

Legal Framework: Cryptocurrencies as Heritable Assets

Although Spain lacks specific legislation on crypto assets, the Directorate General of Taxes and case law agree that cryptocurrencies are transferable assets mortis causa. This means:

• They are integrated into the estate as any other asset.
• They are susceptible to ownership, transfer and encumbrance.
• Heirs acquire legal ownership as of the date of death.
• The provisions of the Civil Code and, where applicable, regional legislation apply.

However, their decentralized nature introduces a critical element: there is no intermediary to certify effective ownership in cases of self-custody. Possession of the private key determines actual control of the asset.

Applicable Taxation: ISD and IRPF

1. Inheritance and Gift Tax (ISD)

The ISD taxes the acquisition of assets by inheritance with rates that vary significantly by autonomous community. For cryptocurrencies:

• Tax base: market value at date of death.
• Valuation: price in euros according to verifiable quotation on recognized exchanges at that exact moment.
• Filing deadline: 6 months from death (extendable).
• Heir’s obligation: prove the existence, ownership and value of the crypto asset.

The obligation falls on the heir, even when they cannot materially access the funds.

2. Subsequent Tax Obligations: Heir’s IRPF

When the heir finally sells the inherited cryptocurrencies:

• Acquisition cost: value declared in the ISD (value at date of death).
• Capital gain: difference between sale price and acquisition cost.
• Taxation: marginal rate in savings IRPF (19%-28% according to brackets in 2025).
• Required documentation: deed of inheritance, ISD self-assessment, exchange receipts. Succession documentation and valuation certifications will be essential before the Tax Authority.

The absence of documentation on the deceased’s historical acquisition cost does not affect the heir, who computes the succession transfer value as acquisition.

Central Problem: Verification and Access to Wallets

Unlike bank accounts or shares, self-custody wallets have no certificate of ownership. Here arises the most complex obstacle: how does an heir prove they are the new legitimate owner of a wallet if they do not possess the private keys?

Without private keys:

• The heir is the legal owner, but cannot dispose of the asset.
• They cannot properly value the asset for the ISD.
• Funds may be permanently lost.
• There is risk of conflict among co-heirs due to lack of transparency.
• Involuntary tax non-compliance may occur.

This is the main reason why digital succession planning requires a specific technical protocol.

How to Integrate Cryptocurrencies into a Will Securely

1. Never Include Private Keys in the Will

Including private keys directly in a will is a critical security error. Wills:

• Are notarized (third-party access).
• Are registered in the General Registry of Acts of Last Will.
• Can be consulted after death.
• Do not guarantee absolute confidentiality for years.

Including seeds or private keys compromises asset security.

2. Correct Structure: Will + Separate Technical Document

The optimal structure combines:

1. Notarial will with specific clauses that:
   • Acknowledge the existence of digital assets.
   • Authorize the executor and heirs to access devices and accounts.
   • Establish an express distribution of digital assets.
   • Designate a digital executor with technological competencies or specialized support.
2. External technical document, separate and securely stored, without explicit keys, which must contain:
   • Inventory of wallets (public addresses).
   • List of exchanges and platforms with associated email.
   • Location of hardware wallets.
   • Recovery protocols.
   • Professional contacts for legal and technical support.

This document must be updated periodically.

Digital Assets Beyond Cryptocurrencies

Digital succession planning is not limited to Bitcoin or Ethereum. The inventory must include:

• Cryptocurrencies on different blockchains (includes balances, accounts on crypto brokers, as well as pending orders, relevant tax history of all trading platforms)
• Fungible and utility tokens.
• NFTs with economic value or royalties.
• DeFi positions (liquidity, loans, staking).
• Technological rights (smart contracts, vesting).
• Traditional digital assets: web domains, monetized social media accounts, cloud files, email accounts, transferable software licenses, neobanks and digital payment methods.

The Organic Law 3/2018 on Data Protection recognizes post-mortem digital rights, allowing heirs to access the deceased’s digital content unless expressly prohibited.

Serious Errors in Digital Inheritances (and How to Avoid Them)

Error 1. Not Leaving Access Instructions

Consequence: irreversible loss of digital assets. Permanently blocked funds.

Solution: Documented protocol, securely stored, periodically updated. Include detailed technical instructions adapted to the heirs’ level of knowledge.

Error 2. Using Insecure Recording Methods

Common dangerous practices:

• Photographing seeds with mobile phone (vulnerable to hacking, cloud backups)
• Storing keys in Word documents or phone notes
• Sending sensitive information by email or WhatsApp
• Writing seeds on paper without physical protection or duplicates

Solution: Hardware wallets, seed splitting, safety deposit boxes, professional testamentary custody services.

Error 3. Not Documenting Exchanges or Platforms Used

Heirs do not know where to look for assets and therefore cannot claim balances. Many exchanges require specific succession documentation and KYC processes for heirs. Without documentation from the deceased about which platforms they used, nothing can be done.

Solution: complete inventory of platforms, including inactive ones.

Error 4. Not Anticipating the Tax Burden on Heirs

Generally heirs—who must settle the ISD—may lack liquidity, forcing them to sell assets (potentially at a bad market moment) to pay taxes

Solution: Prior tax planning that considers:

• Life insurance covering estimated tax burden
• Lifetime gifts with tax benefits according to autonomous community
• Creation of available liquidity to meet taxes
• Family or corporate structures when legally appropriate

Error 5. Not Understanding Subsequent IRPF Taxation

There is a common conceptual error, which is believing that after paying the ISD, there are no more taxes. However, as we have explained, when the heir sells the inherited cryptocurrencies, they generate a capital gain subject to IRPF.

Solution: Advice on optimal timing of sale, loss offsetting, planning of fractional sales in different tax years.

Error 6. Not Properly Valuing Assets

Problem: Incorrect valuation in the ISD generates:

• Penalties for incorrect declaration if undervalued
• Tax overpayment if overvalued
• Problems in computing future capital gains

Solution: Expert valuation reports, use of recognized methodologies, exhaustive documentation of market value at exact date of death with verifiable sources.

Error 7. Not Including Digital Assets in the Will

Many of our clients often find that traditional assets are distributed in the will, but nothing is said about digital assets.

Solution: Testamentary clauses that expressly include “digital assets and accounts, cryptocurrencies, tokens and any assets registered on blockchain technology or digital platforms”.

Error 8. Not Updating Information

In reality, wallet changes, fund migration between platforms, exchange closures, security updates often occur. This means instructions do not reflect the current location of assets.

Solution: Biannual or annual review of digital inventory, updating of access protocols, verification that recovery keys work correctly.

Comprehensive Succession Planning: Professional Steps

Step 1: Complete Asset Inventory

Include traditional and digital assets, with detailed documentation.

Step 2: Professional Asset Valuation

Official real estate appraisals; bank certificates of balances at recent date; expert reports for crypto assets, NFTs and complex digital assets; business valuation if there are shareholdings; documentation of debts and charges that reduce the estate

Step 3: Preventive Tax Analysis

Calculate ISD by autonomous community, possible reductions or tax benefits and future taxation.

Step 4: Will with Digital Clauses

Include access authorization, recognition of digital assets, designation of executor and, of course, a clear and explicit distribution among heirs.

Step 5: Technical Key Document

Separate from the will, secure and updated. With a determined custody method (Notary in sealed envelope with opening instructions, in a bank safety deposit box, in a specialized testamentary custody service)

Step 6: Digital Executor or Specialized Advisor

Essential when there are significant crypto assets. Requires selecting a trusted person with sufficient technical knowledge.

At this point, it is highly recommended to designate a professional digital advisor (specialized lawyer, blockchain consultant) to work alongside the traditional executor.

Step 7: Preventive Structures for Tax Planning

Life insurance, lifetime gifts or asset structures when appropriate.

Step 8: Communication and Periodic Reviews

• Inform heirs (without compromising security) of the existence of digital assets
• Designate contacts: lawyers, tax advisors, blockchain experts
• Establish protocols: what to do immediately after death
• Train heirs: basic concepts of cryptocurrencies and digital security

How Can IN DIEM Help You?

The intersection between succession law, taxation and blockchain technology makes inheritance planning with cryptocurrencies one of the most complex legal areas of the moment. Errors can translate into irreversible losses, serious tax problems and family conflicts.

A professional strategy ensures that traditional and digital assets are transmitted correctly, complying with regulations and preserving the security of the legacy.

Protect your digital legacy with specialized professional advice.

Inheritance planning with cryptocurrencies and digital assets represents one of the most complex legal and tax challenges of contemporary asset law. The intersection between traditional succession regulations, crypto asset taxation and technological security requires a multidisciplinary approach.

Our firm combines legal rigor with deep technical knowledge in blockchain and crypto asset taxation. We offer comprehensive digital asset planning services:

• Complete audit of your traditional and digital assets.
• Drafting of wills with specific clauses for technological assets.
• Key and access custody protocols.
• Preventive tax planning.
• Expert valuation reports.
• Advice on successions with digital assets.
• Tax regularization of previously undeclared cryptocurrencies.

Do not leave the future of your digital assets to chance. Professional planning today prevents irreversible losses and conflicts tomorrow.

Expert Cryptocurrency Lawyers: Málaga, Seville, Madrid, Las Palmas de Gran Canaria, Almería, Huelva, Marbella, Estepona,…

At IN DIEM Abogados and Cryptoveritas 360 we provide our services at all our offices and locations in Spain, offering direct and personalized coverage in Madrid, Seville, Málaga, Marbella, Las Palmas de Gran Canaria, as well as continuous service through our digital channels for clients throughout the country.

Our multidisciplinary team also advises international companies—including Europe, Latin America and Asia—that wish to establish or expand in Spain under the MiCA regulatory framework, whether through obtaining the CASP license from the CNMV or the incorporation of companies and compliance structures adapted to the European market.

Thanks to a hybrid working methodology (in-person and online), we guarantee the same level of quality, confidentiality and efficiency for both local and foreign clients, supporting each project from initial planning to effective regulatory authorization.

We are at your disposal for anything you need. You can reach us via IN DIEM Lawyers Phone (+34) 916 353 892. For urgent cases, you can contact us on IN DIEM 24-Hour Emergency Lawyers Phone: (+34) 610 667 452.

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