Zcash Activates NU7 With 25-Second Block Target and New Fee Reserve

TL;DR: Zcash’s NU7 upgrade activated at mainnet block 3,543,405, reducing target block spacing from 75 to 25 seconds. It also changes how fees contribute to future network security. Faster target blocks do not make every payment final instantly, and node operators need compatible software.

Zcash has crossed an important protocol milestone. The NU7 network upgrade activated in early November at block height 3,543,405, bringing a faster target block interval and changes to the economics of future block rewards. The Zcash Foundation’s Zebra 7 release notes identify the same mainnet activation height and describe the consensus changes required for nodes to follow the chain.

The upgrade is not just a software patch. It changes how Zcash produces blocks and how some transaction fees are handled, while preserving the wider coin-issuance framework.

What moving from 75 to 25 seconds changes

Zcash’s new target is a block every 25 seconds, down from 75 seconds before the upgrade. In theory, that means users and services waiting for several confirmations can receive them sooner. But target spacing is a statistical expectation, not a service-level guarantee: real blocks arrive irregularly, and exchanges or payment processors choose their own confirmation policies.

To prevent a tripling of the number of blocks from mechanically tripling new coin issuance, the upgrade scales the scheduled reward per block and adjusts remaining issuance and halving intervals. The idea is to deliver more frequent blocks while keeping the rate of monetary issuance broadly aligned with the previous schedule.

The node-software detail matters as much as the headline speed. Zebra’s release notes say operators must upgrade to a NU7-compatible client to remain on the consensus chain after the activation point. A user may experience difficulties if a wallet or service depends on an outdated node even when the network itself is operating normally.

A mechanism for later security funding

NU7 also introduces a Network Sustainability Mechanism that directs a portion of transaction fees into a public reserve for future reissuance to miners. Accounts of the upgrade put that reserve contribution at 60% of fees, with the remaining 40% available to miners at the time of collection. The stated design goal is to smooth the eventual decline in subsidy-funded security spending as the network matures.

That is a policy choice within a public cryptocurrency, not free revenue. Money reserved for future rewards is not available in the same way as fees paid immediately to today’s miners. Evaluating the mechanism means examining incentives over time, its interaction with market demand and whether it achieves the intended security effects.

The change also retires support for older version-four transactions, affecting Zcash’s original Sprout pool. This is a reminder that long-running blockchains can carry technical baggage that becomes increasingly difficult to maintain, especially when privacy features and proof systems evolve.

Faster confirmations still need an operational reality check

Zcash offers privacy-preserving transfers, so network improvements should also be assessed against wallet compatibility, scanning performance and the accessibility of shielded payments. The upgrade can improve the underlying capability without ensuring every exchange, mobile wallet or merchant adopts the same features immediately.

NewsBTC previously examined the network’s Zebra synchronisation work ahead of NU7, when the emphasis was on nodes following the chain reliably. Activation does not eliminate those operational responsibilities.

For users and operators, the practical next checks are node versions, observed block times, confirmation requirements and whether particular wallets have published NU7 support notices. The verified milestone is a mainnet rule change; its day-to-day value will emerge through reliability and actual private-payment usage.

This article was written by the News Desk and edited by Samuel Rae.

Featured image: Zcash project emblem (illustrative brand mark for Zcash NU7 network upgrade coverage). Source: Zcash project via Wikimedia Commons (Public Domain simple logo).