Seed Phrase Inheritance
What Is a Seed Phrase?
A seed phrase (also called a recovery phrase or mnemonic) is a sequence of 12 or 24 words that can reconstruct all the private keys in a cryptocurrency wallet. If someone has your seed phrase, they have complete control over every coin in that wallet. There is no second factor, no verification step, and no way to reverse a transaction once it is made.
This makes the seed phrase the single most important element in any Bitcoin inheritance plan. Without it, self-custody Bitcoin cannot be accessed. With it, the Bitcoin can be moved by anyone, anywhere in the world, instantly.
The central challenge of seed phrase inheritance is this: your heirs need the phrase to access your Bitcoin after you die, but nobody should have the phrase while you are alive.
What NOT to Do
Before discussing solutions, it is important to understand the most common mistakes.
Do not put your seed phrase in your will. Wills become public documents after probate is granted in England and Wales. Anyone can apply for a copy. If your seed phrase is in the will, your Bitcoin could be stolen before your executor even begins the administration process.
Do not email your seed phrase. Email is not encrypted by default. Your email provider stores the message on their servers. If your account is compromised at any point — before or after your death — the seed phrase is exposed.
Do not store it in a cloud service. Google Drive, Dropbox, iCloud, and similar services are convenient but not secure enough for this purpose. A data breach, account compromise, or legal subpoena could expose the phrase.
Do not take a photo of it. Photos sync to cloud services, appear in backups, and may be accessible through shared accounts. A photo of a seed phrase on your phone is a security vulnerability.
Do not give the full phrase to any single person. Even someone you trust completely today may not be trustworthy in all future circumstances. Relationships change, people face financial pressures, and a single point of trust is a single point of failure.
Method 1: Metal Backup with Sealed Envelope
This is the simplest approach and suitable for most people with moderate holdings.
How it works:
- Stamp or engrave your seed phrase onto a metal plate (steel or titanium). Products like Cryptosteel, Billfodl, and BlockPlate are designed for this purpose.
- Store the metal backup in a secure location at home — a fireproof safe, a hidden location, or a safe deposit box.
- Create a second copy of the seed phrase and place it in a sealed, tamper-evident envelope.
- Deposit the sealed envelope with your solicitor, with instructions that it is to be opened only upon your death and given to your named executor.
- In your letter of wishes, explain that the metal backup exists, where it is stored, and that a backup copy is held by your solicitor.
Advantages: Simple, no technical knowledge required, works with any wallet.
Disadvantages: A single sealed envelope with a solicitor creates a trust dependency. The solicitor (or someone at the firm) could theoretically open it. Metal backups at home could be found by anyone with physical access.
Best for: Individuals with straightforward setups who trust their solicitor and want minimal complexity.
Method 2: Phrase Splitting
Phrase splitting involves dividing your seed phrase into parts and storing each part in a different location.
How it works:
- Split your 24-word seed phrase into segments — for example, three groups of 8 words each.
- Store each segment in a different secure location (home safe, solicitor, bank safe deposit box, trusted family member).
- In your letter of wishes, explain where each segment is and how to reassemble the full phrase in the correct order.
Advantages: No single location contains the full phrase. Simple to understand.
Disadvantages: Each segment reduces the security of the full phrase. With 8 out of 24 words, an attacker has a significant head start on brute-forcing the remaining words. Losing any one segment means the phrase cannot be reconstructed.
Important warning: Naive phrase splitting (e.g., giving words 1-12 to one person and 13-24 to another) does not provide the security that most people assume. With half the words known, the remaining entropy is dramatically reduced. For strong security with splitting, use Shamir’s Secret Sharing instead.
Best for: People who want simplicity and are comfortable with the reduced security margins.
Method 3: Shamir’s Secret Sharing (SSS)
Shamir’s Secret Sharing is a cryptographic technique that splits a secret into multiple shares, requiring a minimum number of shares to reconstruct the original.
How it works:
- Use a tool that implements SSS (such as the SLIP-0039 standard built into Trezor wallets) to split your seed phrase into, say, 5 shares.
- Set a threshold — for example, 3 of 5 shares are needed to reconstruct the phrase.
- Distribute the 5 shares to different trusted parties or locations: yourself, your spouse, your solicitor, a trusted friend, and a bank safe deposit box.
- Any 3 shares can reconstruct the seed phrase. Fewer than 3 reveals nothing about the original.
Advantages: Mathematically secure — fewer than the threshold number of shares reveals zero information about the secret. Tolerates the loss of some shares (in a 3-of-5 scheme, you can lose 2 shares and still recover). No single party can access the funds alone.
Disadvantages: More complex to set up. Requires a tool that supports SSS. Not all wallets support SLIP-0039 natively. Your heirs need clear instructions on how to combine shares.
Best for: Individuals with significant holdings who want robust security and can handle the setup complexity.
Method 4: Hardware Wallet with Passphrase
Some hardware wallets support an additional passphrase (sometimes called the “25th word”) on top of the standard seed phrase. This creates a completely separate set of wallet addresses.
How it works:
- Set up your hardware wallet with a standard 24-word seed phrase.
- Add a passphrase to create a hidden wallet where you store the majority of your funds.
- Store the seed phrase and passphrase separately — for example, seed phrase in a metal backup at home, passphrase in a sealed envelope with your solicitor.
- Your letter of wishes explains that both pieces are needed.
Advantages: Even if someone finds your seed phrase, they cannot access the hidden wallet without the passphrase. Two-factor protection with physical separation.
Disadvantages: If either piece is lost, the funds are gone. Your heirs need to understand how passphrases work. Not all wallets support this feature.
Best for: Technically confident users who want an extra layer of separation.
Choosing the Right Method
| Factor | Metal + Envelope | Splitting | Shamir SSS | Passphrase |
|---|---|---|---|---|
| Simplicity | High | Medium | Low | Medium |
| Security | Medium | Low-Medium | High | High |
| Redundancy | Low | None | High | None |
| Technical skill needed | Low | Low | Medium | Medium |
| Best for holdings | Under £50k | Under £20k | Over £50k | Over £20k |
These are guidelines, not rules. The right method depends on your circumstances, your trust relationships, and your comfort with technical complexity.
Testing Your Setup
Whichever method you choose, test it before you consider it complete.
- Can your seed phrase be reconstructed from the stored backups?
- Have you verified that the seed phrase correctly restores your wallet?
- Do your heirs know where to find the recovery information?
- Are the instructions in your letter of wishes clear enough for a non-technical person?
A seed phrase inheritance plan that has never been tested is a plan that might not work when it matters most.
Regular Maintenance
Seed phrase storage is not a one-time task. Review your setup at least once a year:
- Are the physical backups still intact and accessible?
- Are the trusted parties still appropriate and available?
- Has your solicitor moved firms or retired?
- Have you changed wallets or created new ones?
Update your letter of wishes whenever your setup changes.
Related Reading
- Multi-Sig Inheritance Explained — An alternative to single-key storage that eliminates single points of failure.
- How to Pass Bitcoin to Your Family — Recovery packs, practice sessions, and the full handover plan.
- Crypto Will Writing Guide — Why your seed phrase should never appear in your will.
- Stefan Thomas: 7,002 BTC Locked Behind a Password — What happens when a single security device becomes the only point of access.
- Forgotten Wallets: Millions of Bitcoin Lost — The quiet tragedy of seed phrases that were never backed up.