Storing Bitcoin Safely: The Complete Custody Guide

Storing bitcoin safely means: you hold the private key yourself, and there is a backup of it that survives fire, theft and your own death. For small amounts a wallet app is enough; from a few thousand euros or francs, a hardware wallet with the seed phrase on metal. For very large amounts, add multisig.

Why custody decides everything

You can do everything right: buy cheaply, save regularly, hold for years. If in the end your bitcoin are stolen, go down with an exchange or can't be found by your family, it was all for nothing.

Bitcoin has no bank that reverses a wrong transfer and no customer service that resets a password. That is by design: nobody can block your coins or take them away. But it also means that security is up to you.

The good news: safe custody is not expert knowledge. It consists of a few rules that you set up once and then rarely touch.

What you are really storing: keys, not coins

Your bitcoin are not on your phone or your device. They are recorded in the blockchain, the public ledger that every bitcoin node keeps. What you own is a private key: the right to move those coins. What a blockchain is and how a payment works is explained in the beginner's guide to bitcoin.

A wallet is the program or device that manages this key and signs payments with it. If the wallet breaks, the coins are not gone. You only need the key to open them again in a new wallet.

That's what the seed phrase is for: 12 or 24 English words that the wallet shows you once during setup. All your keys can be recalculated from them at any time, with any compatible wallet anywhere in the world.

The options compared: from exchange to multisig

There are four common ways to store bitcoin. They differ in who holds the key and how easily you can lose it.

Exchange or app: convenient, but not yours

On an exchange, your account shows a number. The coins sit in the provider's wallets, mixed with those of all other customers. Legally, you have a claim against the company.

Since the end of 2024, the MiCA regulation has applied in the EU. It requires providers to hold their customers' coins separately from their own assets, including in insolvency. In Switzerland, the Debt Enforcement and Bankruptcy Act has governed this since 2021. What the EU rules mean for your own wallet is in the article MiCA: what EU regulation means for bitcoin holders. That helps, but only if the coins are actually still there. What happens when they are missing is shown by the exchange collapses from Mt. Gox to FTX: customers waited years and often got only part of their money back.

There is no deposit insurance for bitcoin like there is for bank accounts. An exchange is right for buying, not as a vault for years.

Wallet app: the entry into self-custody

A bitcoin wallet app on your phone generates the key on your device. Nobody but you has it. It's free and set up in five minutes.

The catch: a phone is connected to the internet, has many apps and is easily lost. For amounts you would also carry in your wallet, that's fine. For your savings, it isn't. Use an app that supports only bitcoin and whose code is open for anyone to inspect.

Hardware wallet: the standard for savings

A hardware wallet is a small device that generates the key and never gives it out. Your computer or phone only prepares a payment. It is signed on the device, after you have checked and confirmed the amount and address on the device's own screen.

Even if your computer is infected, the malware can't send anything without your confirmation on the device. Hardware wallets cost about 60 to 250 euros or francs, depending on the model. There are devices that support only bitcoin, some of them from Switzerland. Fewer features means a smaller attack surface. Which models exist and how they differ is shown in the hardware wallet comparison.

Multisig: no single mistake costs everything

With multisig, a payment needs several keys, typically 2 of 3. The three keys sit on different devices in different places. If one is lost or stolen, your coins are neither gone nor in someone else's hands.

The price is complexity: besides the seeds, you have to back up the wallet descriptor, which records which keys belong together. Without it, the wallet cannot be restored. Multisig is worth it when the amount is so large that a single mistake would change your life. How to set up a 2-of-3 wallet and what you need to back up is explained in the article Multisig wallet: more security through several keys.

And ETPs?

A bitcoin ETP in a brokerage account has a completely different purpose: you hold a security, and a service provider holds the bitcoin. You don't have to look after keys, but you can never use the coins yourself or protect them from the issuer. The differences from real bitcoin are described in the guide to buying bitcoin.

Which custody suits your amount

There is no fixed threshold, but there is a simple question: how hard would the loss hit you? That gives you a level, which you extend as the amount grows.

The levels aren't only about today's amount. If you hold bitcoin for years, you are protecting holdings whose value can rise or fall sharply. Your custody should also fit what they might be worth in a few years.

What your holdings are worth today in euros, francs and sats, you can convert here:

Where the price stands today relative to the trend is shown on the Power Law page. The model itself is explained in the article on the Bitcoin Power Law.

Backing up your seed phrase properly

The seed phrase is the real value. The device can be replaced; the words cannot. Almost all losses in self-custody come down to a poor seed backup.

How to do it right:

• On paper, then on metal. Copy the words by hand during setup. For amounts that matter to you, transfer them to a metal plate: steel survives fire and water, paper doesn't.
• Numbered and complete. Every word with its number. The order matters.
• In a place you control. An inconspicuous, dry spot at home or a bank safe deposit box. Decide deliberately who may look where.
• Separate from the device. Anyone who finds the device and the seed together only needs the PIN.

What you never do:

• no photo, no screenshot, no cloud storage, no notes app, no password manager
• never type the words into a website, an app or a form, except for a genuine recovery on your own device
• never tell anyone, not even "support": no reputable provider will ever ask for your seed phrase

Which metal survives a house fire, how many copies you need and why you should never split a seed in half is in the article Storing your seed phrase safely: metal backups and mistakes.

Anyone who asks for your words wants to rob you. That is the most common trick in bitcoin fraud, by email, phone, social media or fake app. The other tricks and their warning signs are in the article Recognising bitcoin scams.

The passphrase: the second layer of protection

Many wallets also allow a passphrase, often called the "25th word". It is a freely chosen word or sentence that, together with the seed phrase, opens an entirely different wallet.

The advantage: if someone finds your seed phrase, they see an empty or small wallet. Your real coins stay invisible. That also protects you if someone puts you under pressure.

The disadvantage: if you forget the passphrase, the coins are lost, even with the seed. So it needs its own backup, separate from the seed. A passphrase is worth it if you can really keep up the extra care.

Storing bitcoin safely in seven steps

This is how you get from the exchange to your own custody. Every step in detail, with a recovery test and a first withdrawal, is shown in the guide Setting up a bitcoin wallet.

1. Choose a device or app. To start, a bitcoin-only wallet app; for savings, a hardware wallet directly from the manufacturer.
2. Set up, write offline. The device shows you the seed phrase. Copy it with no camera nearby. Set a PIN.
3. Check the seed. Most devices quiz you on individual words. Compare every word with the word list.
4. Test the recovery. Send a small amount, reset the device, restore from the seed (see the tip above).
5. Check the address on the device. Generate a receiving address and compare it on the device's screen, not just on your computer. Malware likes to swap copied addresses.
6. Small first, then everything. Send a small amount from the exchange first. Once it has arrived, the rest follows. In the EU, for withdrawals of €1’000 or more you often have to prove that the wallet is yours.
7. Store the backup. Seed on metal in a safe place, separate from the device. Write an emergency plan (see below).

How to set up a savings plan and withdraw regularly is shown in the guide to buying bitcoin. You learn the basics from key to backup step by step in the academy, stage 2: understand and secure.

The most common storage mistakes

Most bitcoin are lost not through sophisticated hacks, but through simple mistakes:

• Forgetting coins on the exchange. Convenience is the biggest risk. Schedule regular withdrawals, for example every month or above a certain amount.
• Seed only in digital form. A photo in the cloud is enough for an attacker who takes over your account.
• Only one backup in one place. A house fire destroys device and paper at the same time.
• Falling for "support". Fake apps, emails and calls ask for your words or a "verification".
• Address not checked. A payment to the wrong address is final.
• Nobody knows. Without instructions, your family will never get to the coins.
• Built too complicated. A setup that you yourself won't understand in two years is a risk. Simple and understood beats clever and forgotten.

Emergency plan: so your family can get to the coins

Bitcoin in self-custody have no account that an heir can present to the probate court. Without the seed and instructions, they are lost to your family, even though legally they are part of the estate.

A good emergency plan answers three questions:

1. What is there? Which wallets, roughly how much, and where devices and backups are kept.
2. How do you get to it? Instructions that someone without expert knowledge can understand: which wallet app, where seed and passphrase are, how to restore.
3. Who can be trusted? A person who knows bitcoin and will help in an emergency, without having access themselves.

Keep the plan separate from the seed, for example with your emergency documents. It reveals where the keys are, not the keys themselves. How to keep your will, emergency letter and keys cleanly separate is shown in the article Inheriting bitcoin. How to raise the subject with the people it affects is in the article Talking about bitcoin with your partner and family.

Discretion: the underrated security

The best custody does little good if everyone knows you have a lot of bitcoin. No device helps against violence.

• Don't talk about your holdings. Not among friends, not on social media, not with screenshots.
• Keep parcels inconspicuous. Have hardware wallets delivered to an address that doesn't reveal how much you own, and dispose of packaging neutrally.
• Plan for coercion. A small wallet you can hand over if necessary, and a passphrase for the rest, are a proven protection.

Where your holdings become visible and how to protect your home, mail and data is shown in the article Discretion and physical security for bitcoin holders.