Bitcoin may be heading for one of its most significant upgrades in years BIP-119, also known as OP_CHECKTEMPLATEVERIFY (CTV). First proposed in 2019 by developer Jeremy Rubin, this Bitcoin Improvement Proposal (BIP) has recently regained attention from developers and crypto firms alike. With growing support from the Bitcoin community, some now believe BIP-119 could finally reach consensus by the end of 2025, and possibly as early as the end of this year.

Developer Jeremy Rubin

This proposed change aims to bring new capabilities to the Bitcoin network, especially around security, smart contract-like functionality, and Layer-2 scaling solutions such as the Lightning Network and the emerging Ark Protocol. Here’s what it all means, why it matters, and what challenges lie ahead.

What is BIP-119 and Why Is It Important?

At the heart of BIP-119 is a new opcode called OP_CHECKTEMPLATEVERIFY, which introduces a concept known as covenants. In simple terms, covenants allow Bitcoin users to restrict how their BTC can be spent in the future. This sounds technical but the potential benefits are massive.

An example of smart vaults in practice. Source: Jeremy Rubin via utox.org

With covenants, users could set up “smart vaults”, which allow pre-set spending rules. For instance, you could create a cold wallet that only allows 0.1 BTC to move to a hot wallet each week, reducing the risk of a full compromise if your private keys are ever stolen. These vaults could serve personal users and businesses looking to strengthen their custody practices.

Another major application is the support for more advanced Layer-2 solutions, like Lightning and Ark, which could benefit from covenants’ security and control features. These tools are designed to make Bitcoin faster, cheaper, and more practical for everyday use, something the base layer alone still struggles with.

Support From Developers and the Community

For any Bitcoin upgrade to go forward, it must earn broad support from the community, a long and sometimes painful process due to Bitcoin’s decentralised nature. But BIP-119 seems to be gathering real momentum.

On 9 June 2025, 66 Bitcoin developers and contributors signed an open letter urging the community to review and prioritise BIP-119 and a related proposal (BIP-348). The list included well-known names like Jameson Lopp and Andrew Poelstra, and contributors from major Bitcoin-focused companies such as Luxor Mining, Anchorage, and Alpen Labs.

Bitcoin hash rate is centralized compared with nodal distribution. Source: Hashrate Index

These developers stressed the practical benefits that BIP-119 could bring, including better scalability, security, and privacy. They believe the changes would improve not only Bitcoin itself but also the tools built on top of it, such as payment channels, bridges to other blockchains, and even more complex DeFi-like applications.

Steven Roose, CEO of Second and a strong backer of the Ark Protocol, said in a recent interview that he believes consensus could form by the end of 2025. “This protocol upgrade would enable the implementation of Eltoo-style channels, also called Lightning Symmetry,” he said, a feature that could make Bitcoin payments safer and more efficient.

What Could BIP-119 Unlock?

BIP-119 could lay the groundwork for a wide range of powerful new Bitcoin use cases:

1. Smarter Self-Custody with Vaults
Vaults powered by covenants could allow individuals and businesses to predefine how much Bitcoin can be moved, to which addresses, and over what time period. This drastically reduces the damage that can be caused by wallet hacks or mismanagement.

2. Improved Lightning Network and Layer-2s
The Lightning Network has already made Bitcoin faster and more scalable. However, it still suffers from complex technical limitations. BIP-119 could make Lightning more robust and user-friendly. It could also boost new projects like Ark, a Layer-2 solution that uses Bitcoin’s base-layer transactions to enable faster, more private, and cheaper transactions.

Receipt from a Florida Steak & Shake on July 3, 2025, using the Bitcoin Lightning payment method. Source: British Blockchain Association

3. Cross-Chain Bridges
One exciting possibility is bridging Bitcoin with smart contract platforms such as Ethereum, Polygon, and Avalanche. With BIP-119, developers could more easily create bridges using Bitcoin Virtual Machines (BVMs), allowing Bitcoin to interact with the broader DeFi and Web3 ecosystem.

4. Discreet Log Contracts
These are a type of private contract where multiple parties agree to send BTC based on the outcome of an external event, such as a sports match or market price without revealing details on the blockchain. BIP-119 could make these contracts more efficient and secure.

Why Is It Taking So Long?

Bitcoin upgrades don’t happen quickly and for good reason. The Bitcoin network has no central authority, no CEO, and no single decision-maker. Every proposed change must go through a decentralised process involving miners, node operators, developers, and users.

The last upgrade, Taproot, was activated in 2021 and took several years of community discussion. While it introduced helpful privacy and efficiency improvements, it also gave rise to controversial use cases like Ordinals (NFT-like assets on Bitcoin), which left some developers cautious about future upgrades.

Jeremy Rubin initially proposed using a Speedy Trial method for BIP-119, a way to activate the change if 90% of miners signal approval. But this was criticised by some for giving too much control to miners. Others argue for a User Activated Soft Fork (UASF), which would require a majority of full node operators to support the upgrade, a slower but more decentralised and democratic approach.

Despite the complexity, the mood appears to be shifting. Earlier critics of BIP-119 have either gone quiet, changed their minds, or decided not to oppose the process. With active discussions now underway and increased developer attention, a decision on direction may come before the end of the year.

A Big Deal, If It Happens

Experts agree that BIP-119 could be a game-changer for Bitcoin, but only if it’s implemented properly. Daniel Gray of Fidelity Digital Assets highlighted that BIP-119 “adds an additional level that could potentially bring more comfort to self-custody users,” while also improving the broader Bitcoin economy.

Naseem Naqvi, president of the British Blockchain Association, believes BIP-119 could finally address long-standing Bitcoin limitations like high fees and slow confirmations, making the network far more usable in the real world.

If the Bitcoin community reaches consensus, the code will need to be integrated into Bitcoin Core, the most widely used software client. Even then, actual implementation could take another year or two, meaning BIP-119 may not be live until late 2026 or beyond.

Still, the path is clearer than ever. If activated, BIP-119 could unlock a powerful new era for Bitcoin: safer wallets, faster payments, private smart contracts, and real interoperability with the wider crypto world.