Zcash developers have agreed on block 3,543,405 as the planned activation point for Network Upgrade 7 (NU7), bringing the privacy-focused blockchain closer to introducing 25-second blocks around November 5.
Summary
- Zcash developers have selected block 3,543,405 for NU7 activation, expected around November 5.
- The upgrade will reduce target block times from 75 seconds to 25 seconds, cutting confirmation delays.
- NU7 introduces a mechanism that temporarily removes 60% of transaction fees from circulation.
- Funds remaining in Zcash’s legacy Sprout pool will become unspendable after the upgrade.
- The activation proposal has received two approvals but still requires final integration into the deployment specification.
According to an October 20 GitHub proposal submitted by developer Sean Bowe, the activation height was agreed upon during a meeting of Zcash Improvement Proposal (ZIP) editors, although the change still requires final integration into the network’s deployment specification.
Meanwhile, the proposed block height establishes a specific point at which Zcash would begin applying the new consensus rules, replacing the provisional November 5 timetable with a block-based activation target.
Bowe’s proposal received approvals from developers ValarDragon and str4d on October 20. The pull request remained open during the October 21 review, with the official NU7 deployment specification still listing the mainnet activation height as undecided.
The proposal contains another scheduling detail: block 8,939,664 is designated for the future reissuance of funds accumulated under NU7’s Network Sustainability Mechanism.
Before activation, the selected height must be incorporated into the deployment specification and compatible node software.
The November timetable follows developer agreement on NU7 reached in September, when participating engineering teams settled on the upgrade’s principal features and established the mainnet target.
In the September 18 development timeline, Zcash developer Sean Bowe identified October 20 as the date for confirming the activation height following experience with the test network.
The network has already completed its initial testnet activation. On October 4, NU7 became active at testnet block 4,465,026, allowing developers to evaluate the proposed changes before mainnet deployment.
As crypto.news previously reported, the testnet rollout introduced faster target blocks, updated transaction rules and the planned mechanism for handling network fees.
NU7 cuts Zcash block times from 75 seconds to 25 seconds
Under ZIP 218, Zcash will reduce its target block spacing by two-thirds, producing a new block approximately every 25 seconds instead of 75 seconds.
The adjustment would triple the expected frequency of block production, reducing the time users typically wait for successive transaction confirmations.
For example, three confirmations would take approximately 75 seconds under the new target, compared with 225 seconds under the existing schedule. Actual confirmation times can vary because block production is not perfectly uniform.
The upgrade introduces limits on shielded transaction activity within individual pools and across the network. These restrictions are intended to manage the additional processing and wallet synchronization demands associated with faster blocks.
The Zcash Foundation described those changes in its October 2 Zebra 7.0.0 release candidate announcement, which introduced NU7 support for testnet operators.
Although the block-production schedule is changing, NU7 does not introduce a new transaction format. Existing version 5 and version 6 transactions remain valid under the deployment specification.
The planned changes retain the network’s existing monetary supply cap and preserve its established mining reward halving schedule.
Zcash introduces fee mechanism with reissuance planned for 2031
NU7 will introduce the Network Sustainability Mechanism, which temporarily removes 60% of transaction fees collected in each block from circulation.
Under ZIP 235 and ZIP 237, those funds accumulate in a publicly tracked network balance before being gradually reissued through future miner rewards.
The developers have selected February 2031 as the approximate starting point for reissuance, with the new proposal assigning mainnet block 8,939,664 to that event.
The arrangement does not create additional ZEC beyond the network’s supply cap. Funds paid out through the mechanism must have been removed from circulation or otherwise left unclaimed under the applicable consensus rules.
During September’s coinholder governance poll, approximately 98.9% of participating ZEC supported preserving the existing halving schedule, while 96.6% favored beginning the sustainability mechanism’s reissuance in February 2031.
The same vote recorded approximately 99.9% support for reducing block times to 25 seconds, with nearly 2.4 million ZEC participating.
Sprout transactions will become invalid after NU7 activation
One of NU7’s permanent changes concerns Sprout, the original shielded transaction system introduced when Zcash launched in 2016.
The upgrade disables version 4 transactions, which are required to spend funds held in the legacy Sprout pool.
Consequently, coins remaining in Sprout when NU7 activates will become unspendable under the upgraded consensus rules. Holders must move those funds into a supported pool before activation to retain access.
Version 5 and version 6 transactions are unaffected by this particular restriction.
The deployment specification identifies the Sprout shutdown as part of ZIP 2003, alongside the block-spacing changes, shielded action limits and revised fee mechanism.
The specification permits operators running unsupported software to remain connected at activation, potentially following an incompatible pre-NU7 chain. Deployment instructions therefore require node operators to upgrade their software before the network reaches the selected activation block.
