Zcash NU7 Is Live: 25-Second Blocks and Fee Recycling

Zcash's long-planned NU7 network upgrade is now live. It activated at block 3,543,405 early on Friday, November 6, bringing three times faster blocks and a new way to fund the network's long-term security. When we previewed NU7's 25-second block target in September, the date was still a plan. Now it is on mainnet.

• NU7 activated on Zcash mainnet at block 3,543,405 on November 6, 2026
• Target block time drops from 75 seconds to 25 seconds
• The Network Sustainability Mechanism removes 60% of transaction fees from circulation and reissues them later as block rewards
• Reissuance starts in 2031 and keeps the 21 million ZEC supply cap intact

What Is the Zcash Network Sustainability Mechanism?

Every proof-of-work coin with halvings faces the same long-term question that Bitcoin does. As block subsidies shrink, will transaction fees alone pay miners enough to secure the chain? The Network Sustainability Mechanism (NSM) is Zcash's answer.

Under NSM, 60% of each transaction fee is taken out of circulation. Starting in 2031, those coins are gradually paid back out through future block rewards, spread along a smooth curve on top of the existing halving schedule. The total supply never goes above 21 million ZEC. It was the first project of Shielded Labs, and it builds on an older idea from developer Nate Wilcox once called the Zcash Posterity Fund.

The final design kept Zcash's halvings. Shielded Labs originally proposed replacing them with a smooth issuance curve. Community panels supported that, but coinholders did not, so the team built an alternative that keeps the halvings. It is a good example of Zcash's governance process working as intended.

How Do 25-Second Blocks Change Zcash Payments?

Faster blocks mean quicker first confirmations, which makes private payments feel more responsive. The trade-off with short block times is a higher chance of orphan blocks, valid blocks dropped because another miner's block spread first.

The developers of Zakura tested this. In an 80-node stress test across 11 regions, with every block full of private transactions, they measured a 3.43% orphan rate at 25 seconds against 1.57% at 75 seconds. They expect the live network to stay under 1%, since real blocks are much emptier and mining is more concentrated. That is analysis from the test team, not a guarantee, but it is encouraging.

Other NU7 Changes for Zcash Users

NU7 also caps how much shielded transaction activity fits in each block, which cuts the data wallets must scan to find their payments. It also retires Sprout, Zcash's original privacy pool from 2016, so anyone still holding coins there should check their wallet's guidance.

"NU7 has successfully activated on mainnet," the project's official account posted. For a chain with a careful, coinholder-driven upgrade process, that is a real milestone. Follow more network upgrades in our crypto coverage.

Sources: Decrypt — November 6, 2026; The Block — November 6, 2026.