# Zcash activates NU7, cutting target block time to 25 seconds and sending most fees to a reserve

The upgrade retires the 2016 Sprout privacy pool, and a November 7 snapshot shows that fees have added only 1.12 ZEC to the new reserve, which is 99.7% inherited balance.

- Published: 2026-11-08T05:54:51.727Z
- Canonical: https://polylog.news/crypto/2026-11-08/zcash-activates-nu7-cutting-target-block-time-to-25-seconds
- Publisher: Polylog (Crypto desk)
- Section: crypto
- Sources: [CryptoSlate](https://cryptoslate.com/zcashs-new-security-fund-is-99-7-old-money/), [CoinDesk](https://www.coindesk.com/tech/2026/11/06/zcash-s-landmark-nu7-upgrade-goes-live-speeding-up-private-payments), [crypto.news](https://crypto.news/zcash-targets-nov-5-for-nu7-mainnet-upgrade/), [CryptoSlate (coinholder vote)](https://cryptoslate.com/zcash-holders-vote-to-preserve-halvings-and-defer-recycled-zec-until-2031/), [ZecHub](https://zechub.wiki/start-here/network-upgrades)

Zcash's seventh network upgrade, NU7, [went live on mainnet](https://www.coindesk.com/tech/2026/11/06/zcash-s-landmark-nu7-upgrade-goes-live-speeding-up-private-payments) on November 6 at block 3,543,405, the height [ZecHub had listed](https://zechub.wiki/start-here/network-upgrades) for activation. It is the largest change to the privacy chain's base layer in years. The upgrade cuts the target time between blocks from 75 seconds to 25 seconds under a draft Zcash Improvement Proposal (ZIP), ZIP 218, [according to crypto.news](https://crypto.news/zcash-targets-nov-5-for-nu7-mainnet-upgrade/). Shielded payments therefore reach their first confirmation about three times faster.

Faster blocks would normally speed up issuance. To keep the coin's supply schedule unchanged, NU7 lowers the reward paid per block and lengthens the halving interval, measured in blocks. Coinholders had [voted to keep the halvings](https://cryptoslate.com/zcash-holders-vote-to-preserve-halvings-and-defer-recycled-zec-until-2031/) rather than replace them with a smoothed issuance curve.

NU7 also disables version 4 transactions. That retires Sprout, the original shielded pool from 2016, and anyone still holding coins there had to move them before activation. A Zcash Foundation estimate [cited by crypto.news](https://crypto.news/zcash-targets-nov-5-for-nu7-mainnet-upgrade/) put the pool at less than 23,000 ZEC.

The most debated change is the Network Sustainability Mechanism. Under ZIP 235, at least 60% of each transaction fee goes into a reserve instead of directly to miners, and miners keep the remaining 40%. Coinholders [voted to wait until February 2031](https://cryptoslate.com/zcash-holders-vote-to-preserve-halvings-and-defer-recycled-zec-until-2031/) before any reserve ZEC flows back into block rewards.

A mainnet snapshot taken on November 7 and [analyzed by CryptoSlate](https://cryptoslate.com/zcashs-new-security-fund-is-99-7-old-money/) shows the scale of the problem. A historical seed balance carried in at activation makes up 99.7% of the reserve. Fees collected under the NU7 rules have added 1.12 ZEC. On current transaction volume, fee income is too small to fund the network's security, which still depends almost entirely on new issuance.

## What this means

NU7 changes two things. Exchanges and payment apps now get faster shielded confirmations, and that speed is the channel through which demand for privacy could translate into ZEC usage. The fee reserve, by contrast, barely affects supply today. Miners are still paid almost entirely from issuance, so Zcash faces the same long-run security-budget question as Bitcoin, now with a block time three times faster, which makes discarded blocks more likely. Most coverage treats the reserve as a mechanism that permanently removes coins from circulation, and that reading overstates its effect. Ethereum's fee burn, introduced in August 2021 under EIP-1559, is the closest precedent. That burn reduced net supply only when on-chain demand was high, and had little effect when activity fell. The desk's read is that the reserve will keep growing slowly for months and that ZEC's supply will continue to follow the issuance schedule. That would change only if shielded transaction volume rises far above today's level. Two things would prove this wrong: later snapshots showing fee additions growing fast enough to rival the block subsidy, or a sustained rise in discarded blocks that pushes small miners out and concentrates hashrate.

## What to watch

- The rate of discarded blocks after activation. Shorter block times favor large, well-connected miners, so a sustained rise would mean mining is concentrating.
- Fee additions to the reserve in later mainnet snapshots. They show whether real shielded usage, not the inherited seed, is starting to fund security.
- Whether major exchanges cut ZEC deposit confirmation requirements to match the faster blocks. That is the practical test of the "faster private payments" claim.