Bitcoin improvement proposal BIP-110 is approaching a critical stage in its activation schedule, with mandatory signaling set to begin at block 961,632. The enforcement window had not started at the time of writing, making the immediate development a countdown to the predefined block height rather than an active network-wide rule change. The proposal’s specification sets the mandatory period from blocks 961,632 through 963,647.
BIP-110, formally titled “Reduced Data Temporary Softfork,” would temporarily impose additional consensus restrictions on several methods used to place large amounts of arbitrary data into Bitcoin transactions. Its rules include limits on large data pushes, certain output scripts, Taproot control blocks and other transaction structures. The proposal is designed as a temporary soft fork lasting approximately one year after activation, with existing UTXOs created before activation generally grandfathered from the new restrictions.
Blocks 961632 to 963647: mandatory signalling. BIP-110 nodes reject any block whose header doesn't signal bit 4. No reduced-data checks on transactions – just checking the block header.
Blocks 963648 to 965663: lock in. Signalling no longer enforced. This window exists so the…
— Donal #BIP-110 (@DonalDevine) August 6, 2026
Mandatory Signaling Raises the Coordination Stakes
The deployment uses a modified version of BIP9 with version bit 4 and a signaling threshold of 1,109 blocks out of each 2,016-block difficulty period, equivalent to 55%. If voluntary signaling does not produce an earlier lock-in, BIP-110-enforcing nodes will begin rejecting non-signaling blocks once height 961,632 is reached. That requirement continues until the deployment enters its locked-in state.
The distinction between enforcing and non-enforcing nodes is critical. Publishing a BIP does not automatically change Bitcoin’s consensus rules for every participant, and the Bitcoin BIPs repository explicitly notes that inclusion does not establish community consensus or imminent adoption. The practical consequences therefore depend on which miners, node operators and other infrastructure participants choose software that enforces BIP-110.
If mandatory signaling proceeds as specified, lock-in would occur no later than block 963,648. The proposed restrictions would then become active one difficulty period later at block 965,664 and remain enforced for 52,416 blocks, roughly one year. Block height, rather than a calendar date, governs each milestone, so estimates for when those stages arrive can shift as Bitcoin’s actual block production rate changes.
“Complete” Status Does Not Mean BIP-110 Is Deployed
BIP-110 was moved to “Complete” status on June 25, 2026, but that label can easily be misinterpreted. Under the current BIP process, Complete means the authors believe their work is finished and recommend the proposal for adoption, implementation or deployment. It is distinct from “Deployed,” the status used when a proposal has actually been activated or otherwise put into use.
That makes block 961,632 the immediate operational checkpoint. Before that height, BIP-110’s reference implementation does not require blocks to signal the designated version bit. Once the window begins, nodes enforcing the proposal apply a materially different validation rule to non-signaling blocks. The significance lies in how real network participants respond when the scheduled coordination mechanism becomes enforceable, not in speculation surrounding the countdown itself.
The next relevant evidence will come from miner signaling, node behavior and the chain observed after the threshold is crossed. Until block 961,632 arrives, BIP-110 remains in its pre-enforcement phase, with the more consequential questions around coordination and compatibility still ahead.