How to use the Bitcoin Key Backup Record

• A printer, printing at actual size
• A pen with archival pigment ink. Not pencil, which smudges and fades. Not gel or rollerball, which run when wet.
• The device or software holding the key
• Twenty uninterrupted minutes, offline, somewhere you're not overlooked

Print on the heaviest plain paper your printer takes. Avoid glossy stock, because ink sits on the surface and smears.

Set your print dialog to 100% / Actual Size. Not "Fit to page", not "Shrink to fit". Browsers default to scaling, and a scaled sheet has boxes too small to write in.

Sheet 1 carries a calibration ruler. After printing, measure it. If the line is not 100mm, the page was scaled, so change the setting and reprint. The ruler is the ground truth, not the on-screen preview.

Choose the paper size that matches your printer's tray. A4 gives marginally larger boxes; Letter is otherwise identical.

Print Sheet 4 once for every person who will hold any part of this backup. It contains no secrets, and whoever ends up holding only Sheet 3 needs the handwriting key and the warnings just as much as you do.

Master fingerprint. Eight hexadecimal characters that identify this key. Your device shows it during setup, and wallet software shows it whenever you import the key.

If you use a passphrase, load it first and record the fingerprint shown with the passphrase applied. That is the value that appears in your descriptor, and how a future recoverer confirms the passphrase is right.

Hex uses only 0-9 and a-f. There is never an o, l, s, g or z, so a circle is always zero and a bare vertical stroke is always the digit one.

Key origin. Which device or software created the key, and what version. Some vendors have had derivation quirks in specific firmware versions, so record it.

If the entropy was imported, say where the key came from and what else has ever held it. An imported key's security is capped by the weakest environment it has ever touched: a phone wallet from 2017, a paper backup someone once photographed, an exchange that generated it for you. Nothing else records this, and it becomes unknowable later. If the honest answer is uncomfortable, move the funds to a fresh key rather than document the problem.

Multisig table. Leave it blank for single-signature wallets. The derivation path belongs to each wallet, not to the key: the same device used in a single-sig and two multisigs uses three different paths. Fill in one row per wallet.

The descriptor checksum is the eight characters after the # at the very end of the descriptor:

wsh(sortedmulti(2,[...]))#tjg09x5t

It never contains b, i, o or the digit 1. So when you read it back: a circle is always zero, a bare vertical stroke is always l, and a shape like b is always 6.

The checksum catches a transcription error in a descriptor you already have. Eight characters cannot reconstruct one.

Write in capitals if it helps legibility, and don't join letters up.

Fill in the word numbers. Each BIP39 word has a position from 1 to 2048, and your wallet software will show them. Handwriting degrades, ink fades, and flight and fight look identical after fifteen years in a drawer. #712 does not.

Strike through every unused row. A sheet with twelve words and twelve blanks is ambiguous; a sheet with twelve words and twelve struck-out rows is not.

Only the first four letters of each word are needed to identify it. And the final word encodes a checksum, so a single mistyped word is almost always rejected outright by wallet software: a phrase that "almost works" means a transcription error, not lost funds.

Leave this sheet blank and destroy it if you don't use a passphrase.

Choosing one. Use four or more words from the BIP39 English wordlist, all lowercase, separated by single spaces. Nothing else: no capitals, no punctuation, no accented letters, no emoji, and never a space at the start or end.

Accented and unusual characters are normalised differently by different wallets, so the same passphrase can open different wallets depending on the software. A trailing space is invisible on paper and unguessable. Each is a way to lose funds while believing the backup is fine.

Write one character per box, leaving a box empty for each space.

Where this sheet lives is the real decision.

For a single-signature wallet, storing Sheet 3 beside Sheet 2 cancels the passphrase out entirely. Anyone who finds the pair has everything. Splitting them is the whole point of having a passphrase.

For multisig, keeping them together is usually correct. One compromised key still can't spend, and the far greater risk is that you or your heir never recovers the passphrase at all.

If you split them, complete the bottom block: copy the master fingerprint across, and name the person holding the seed words. Sheet 1 has the mirror field for their contact details.

This sheet is not secret. Print it for every holder, and give it to your heir now, not on your death. Someone reading "never type these words into a website" for the first time during a bereavement is already at risk.

Fill in the handwriting key while you're still the person who can read your own writing. It takes one minute, and it is what tells a future reader whether the mark you made was a zero or an o, a 1 or an l.

Transfer the seed words to stamped or punched stainless steel, which survives fire and flood. Keep the paper for what the steel can't hold: the fingerprint, the paths, the instructions.

Keep copies in at least two separate buildings. A single location is a single fire.

Don't laminate. It traps moisture against the paper, and you can't add to a sealed sheet later, which you will want to do when you complete the test log or add a wallet.

Use a tamper-evident bag and sign across the seal, so you can tell whether a sheet has been read.

A bank safe deposit box is secure but may be sealed on your death, exactly when your heir needs it. A home safe is accessible but is the first place a burglar looks. Most people end up using both.

Restore the seed onto a spare device or into offline wallet software, confirm it produces the same master fingerprint written on Sheet 1, then wipe the test device. Record it in the log on Sheet 4.

Repeat every year or two, and after every house move. Moves are when backups get separated from the people who know what they are.

If you use a passphrase, test the seed and passphrase together. Testing only the seed proves nothing about the half you're most likely to get wrong.

There is no emergency. Funds don't expire. Rushing is how people lose money at this stage.

Read Sheet 4 first, in full. Then check whether Sheet 1 lists a multisig wallet. If it does, the seed words are not enough on their own, and you must locate the separate descriptor backup first. Sheet 1 records where it was kept.

If you need help, ask a Bitcoin professional you have verified independently: a firm with a real address and a reputation, never someone who contacted you. Show them Sheet 4 and nothing else. A trustworthy helper will never need to see your seed words.