Zcash Activates NU7 Upgrade, Cutting Block Times to 25 Seconds

Zcash activated its NU7 network upgrade on mainnet at block height 3,543,405 on Nov. 5, cutting target block times to 25 seconds from 75 seconds. Block rewards will be adjusted to keep the pace of new ZEC entering circulation roughly unchanged. The number of blocks between halvings will triple. Another major change is the Network Sustainability Mechanism, developed by Shielded Labs. The NSM aims to address a longstanding proof-of-work issue: whether transaction fees alone can maintain adequate network security as block subsidies decline. Under the mechanism, 60% of Zcash transaction fees will be removed from circulation and gradually reissued through future block rewards. The design preserves the 21 million ZEC supply cap. Reissuance is set to begin at block 8,939,664, expected in 2031. Recycled funds will be distributed along a smooth curve on top of the existing halving schedule, not replace it. Jason McGee, executive director of Shielded Labs, which supports development of the Zcash ecosystem, said in a tweet: "This is a huge milestone for Shielded Labs. The NSM was our first project and is our first major mainnet deployment. It builds on an idea Nate Wilcox proposed years ago to help sustain the network over the long term. At the time, it was called the Zcash Posterity Fund." NU7 also disables version 4 transactions, making funds left in the original Sprout privacy pool unspendable under the new rules. About 12,224 ZEC remain locked in that pool. A separate proposal under consideration would require Zcash Community Grants to contribute 50,000 ZEC from its treasury to the mechanism. If approved, the contribution could further support future block rewards as the existing subsidy declines. ZEC has had a strong run, gaining more than 150% year-to-date in 2026. It jumped from trading in the $500s to a multiyear high of $1,693 in September. The rally pushed ZEC into the top 10 crypto assets by market capitalization. After the upgrade, ZEC briefly fell to around $1,222, recovered to $1,322, then pulled back again. It was recently trading near $1,290.