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Key Takeaways
- Bitcoin Core developers are proposing to remove the legacy opt-in RBF signal from wallet software now that full-RBF has made it redundant.
- The change is wallet-level only and has no effect on consensus rules or anyone’s ability to bump fees.
- The main coordination challenge is getting wallets to agree on a common replacement value to avoid creating new privacy fingerprints.
Bitcoin Core developers are discussing a proposal to remove opt-in replace-by-fee signaling from wallet software, arguing the feature has become redundant since full-RBF became the network’s standard policy. The change is a wallet-level adjustment with no effect on Bitcoin’s consensus rules or anyone’s ability to bump transaction fees.
Full-RBF Made the Opt-In Signal Redundant in October 2024
Replace-by-fee, or RBF, allows a sender to replace an unconfirmed transaction with a new version that pays a higher fee, incentivizing miners to prioritize it. When Bitcoin Core first introduced the feature under BIP 125 in 2016, senders had to actively opt in by setting a specific field in their transaction called nSequence, signaling to the network that a replacement might follow.
Bitcoin Core 28.0, released in October 2024, enabled full-RBF as the default mempool policy, meaning every unconfirmed transaction is now treated as replaceable regardless of whether the sender set the opt-in signal. That change made the BIP 125 signal redundant. The network no longer needs it to process replacements.
Developer rkrux raised the proposal on the Bitcoin developer mailing list, writing:
There is an intention in the bitcoin core wallet to remove the BIP 125 RBF signaling in transactions for which a PR is raised. The primary reason for its removal is because ever since full-RBF became a standard policy, this signaling has become redundant.
Removing the Signal Cleanly Requires Coordination Across Wallets
The complication is that nSequence is a mandatory field. Wallets cannot simply leave it blank. Every transaction must carry a value in that position, which means removing the opt-in signal requires choosing a replacement value rather than just deleting it.
If different wallets switch to different values, their transactions become distinguishable on-chain, making it easier for chain analysis firms to identify which wallet software produced a given transaction. That is precisely the fingerprinting problem the proposal is trying to solve.
Bitcoin Core contributor Murch noted that roughly 75% of transactions already use one specific sequence value, known as MAX-2. Joining that majority rather than picking a different value is the most effective way to avoid standing out.
Wallet Developers Need to Agree on a Shared Value to Avoid New Fingerprints
The proposal targets Bitcoin Core’s built-in wallet specifically. Other wallet implementations, such as Electrum and hardware wallet software, would need to adopt similar changes independently.
The discussion is aimed at reaching a shared standard across the broader wallet ecosystem so that the transition does not inadvertently create new fingerprints by making some wallets look different from others.
No pull request has been merged yet. The mailing list thread reflects an early-stage coordination effort among developers rather than a finalized code change.
