Recover Electrum Custom Word Extension: What it is and How to Do it

The “Electrum custom word extension” has caused a lot of confusion for some Bitcoin holders. Although this extra word or phrase functions like the optional passphrase found in other crypto wallets, there are a lot of questions about how to use it for Electrum wallet recovery. Plus, as Github discussions on the naming of this " Electrum extra word" show, people can’t agree on this feature’s official name, finding and interpreting info online is extra challenging.

Whether you know it as the “Electrum 13th word,” the “seed extension,”, “custom word extension” or the “Electrum passphrase,” it’s important to clear away any misunderstandings so you know how to use it for wallet recovery. Let’s break down what the Electrum custom word extension is and what to do if it isn’t working.

In essence, the Electrum custom word is an optional piece of information you add on top of your standard 12-word Electrum seed phrase. This could be as simple as a single word or as complex as a phrase with numbers and special characters.

The purpose behind Electrum’s seed extension is like any other optional passphrase: Greater security. Even if a thief discovered your 12-word seed phrase, they would need the correct custom word to access funds stored on this wallet. So, if someone pressured you to reveal your Electrum seed phrase, you have plausible deniability and can share your full seed while partially protecting crypto hidden in a seed extension wallet. On the other hand, if you lose or forget this Electrum seed extension phrase, there’s no way to access or recover the Bitcoin stored here.

Developers introduced the Electrum custom word extension as far back as the Electrum Release 2.7.0 (Oct 2 2016). But even at that early stage, there was debate within the Electrum community over what to call it. You can still see discussions on GitHub about this topic, with terms like “seed extension,” “custom word,” “custom string,” and “passphrase” used interchangeably in the community. Unfortunately, this early mix-up with basic terminology continues to contribute to a lot of confusion.

Both the Electrum custom word and a BIP-39 passphrase act as an additional layer of security on top of a seed phrase, and both open a completely different wallet when entered incorrectly. For everyday users, the experience of using either of these phrases feels nearly identical.

​However, Electrum doesn’t use the BIP-39 wordlist. Electrum uses a proprietary seed-generation system and its word list is therefore specific to Electrum seeds. This means that Electrum custom words are only compatible with Electrum seeds. By contrast, BIP-39 passphrases work with all BIP-39-compatible wallets, such as Ledger, Exodus, or Trezor.

If you need more details on Electrum’s seed or general advice on restoring this wallet, you can read ReWallet’s comprehensive Electrum wallet recovery guide.

Setting up a custom word in Electrum is straightforward, but be sure to take your time so you avoid mistakes like typos or misspelling your phrase: ​

1. Launch your Electrum Wallet and select “File” then “New/Restore.”
2. Enter a new wallet name.
3. If you already have a wallet and want to add a custom word, click “Standard wallet,” “I already have a seed,” then enter your existing seed phrase.
4. If you’re setting up a new wallet, click “Standard wallet,” “Create a new wallet,” and write down the seed phrase Electrum displays.
5. Click the “Options” button.
6. Choose “Extend this seed with custom words.”
7. Carefully enter and record your extra seed word or phrase,
8. Complete the wallet setup as normal.

If you already have an Electrum wallet secured with a custom word and need to restore it, the process closely mirrors the setup flow: ​

1. Open Electrum and select “File” then “New/Restore.”
2. Choose "Standard wallet" and then “I already have a seed.”
3. Before typing your seed, click the “Options" button in the lower-left of the seed entry screen.
4. Check the box “Extend this seed with custom words” and confirm.
5. Enter your 12-word Electrum seed phrase.
6. On the next screen, Electrum will ask for your custom word. Enter it exactly as you documented it.
7. Complete the remaining setup steps. Your wallet and its funds should now be accessible.

If you entered your correct seed phrase and your custom word but your wallet is empty, there’s a good chance the custom word isn’t correct. In many cases, either you entered this word incorrectly, or there’s a bug that’s preventing a seed extension recovery.

Any differences between the actual and wrong custom word will create a completely different Electrum wallet address. Unfortunately, Electrum won’t tell you if you’ve entered a wrong custom word, so you have to be extra vigilant about common mistakes, like:

• Capitalization errors: “Password,” “password,” and “PASSWORD” all produce different wallets.
• Spacing: Similar to spelling or capitalization issues, you’ll create a different wallet if you include even one extra space when entering your Electrum passphrase.
• Similar character confusion: Characters like “0” (zero) versus the letter “O” or the number “1” versus “l” (lowercase L) are common culprits.
• Wrong seed paired with correct custom word: If you have multiple Electrum wallets, you may be entering the right custom word with the wrong seed, or vice versa.

It’s also possible that there might be bugs in certain versions of Electrum that can affect custom word extension recovery. These issues have appeared on Electrum's GitHub repository and can cause situations where your custom word doesn’t restore the wallet as expected.

If you suspect you’re dealing with one of these bugs, you’ll need the guidance of a professional crypto recovery expert to navigate the Electrum recovery process. At ReWallet, we’re familiar with these more complex issues and have helped users recover Electrum wallets affected by them. Reach out to our professional crypto recovery service for an assessment to get started with your Electrum wallet recovery.

If your wallet shows no balance after entering your seed and custom word, don’t give up hope. There are strategies and resources you can use to increase your odds of a successful Electrum wallet recovery.

First, think back to the types of passwords you typically used when you set up your Electrum wallet. If you have any old password books or documents, you might get some clues here to generate ideas. Be sure to write down every variation of the custom word you think you might have used, paying careful attention to the minor details like capitalization and spaces.

When you have a shortlist of potential passphrases, use each variation and note each attempt in a log so you don’t repeat the same one. Also, always double-check that you’re using the correct seed phrase associated with this passphrase if you have multiple Electrum wallets.

If your best efforts at Electrum recovery still aren’t producing results, it’s time to contact a professional crypto wallet recovery service. ReWallet’s team has helped many clients resolve Electrum wallet recovery issues, including cases with Electrum custom word extensions.

Reach out to ReWallet today to discover all your options for a successful Electrum wallet recovery.