The Zcash NU7 upgrade has its mainnet block: developers picked height 3,543,405. The number was agreed at a meeting of the ZIP editors on 20 October 2026 and written into pull request #1405 in the zcash/zips repository, opened by Sean Bowe and approved the same evening by Dev Ojha of Valar Group and Jack Grigg. At 06:30 UTC on 21 October the request was approved but not yet merged. The only node build carrying the height was a Zakura pre-release published a few hours earlier; Zebra, the Zcash Foundation’s node, had not shipped it. By Coindaro’s own arithmetic from the current chain tip, the block should arrive around 5 or 6 November.
The Zcash NU7 upgrade is the largest change to how the network runs in years. Blocks come three times as often, every 25 seconds instead of 75. Each block pays a third of today’s reward, so the amount of new ZEC per day does not move. Sixty percent of transaction fees will be taken out of circulation into a reserve that only starts flowing back through block rewards from about February 2031. And version 4 transactions stop being valid, which freezes whatever is left in the old Sprout shielded smart contract holding reserves of two or more tokens, supplied by users, that a decentralized exchange uses to execute trades automatically at a price set by a formula.">pool.
ZEC rose about 11% over 24 hours to around $1,260, CoinDesk reported at 04:07 UTC, ahead of the other large coins. Its report places the jump after the height decision without saying one caused the other, and nothing published since shows that it did. Blockchair showed ZEC near $1,257 at 06:31 UTC, for a market value of about $21.4 billion.
Zcash NU7 height 3,543,405: agreed by the ZIP editors, software still to come
The pull request is short. Its description says the height was agreed at the ZIP editor meeting and that final changes to ZIP statuses will come with the merge. It edits ZIP 259, the deployment document for NU7, replacing a placeholder that read “TBD (To be set on OCT 20)” with 3,543,405. The NU7 rules require the height to be a multiple of three, and it is.
The same edit fixes several later dates that depend on it. The third ZEC halving on mainnet moves to block 6,132,390, the end of the current development funding streams moves to that same height, and the reissuance of the new fee reserve starts at block 8,939,664. Grigg’s approval lists the developers who reviewed the change with him, Bowe and Daira-Emma Hopwood among them. In a later comment he wrote that the next step is to move every NU7 ZIP to “Proposed” status, a task Hopwood has taken on. Today they are all still drafts.
The repository was busy that evening. Between 21:44 and 22:33 UTC on 20 October the editors merged a change that rescales the timing parameters of ZIP 318 for the faster blocks and a batch of smaller NU7 fixes. They also promoted ZIP 258, the deployment document of the previous upgrade, NU6.3, to Final. A separate proposal to cut the marginal fee in the ZIP 2009 wallet fee rules to 400 zatoshis was closed without being merged.
The software is behind. The latest Zebra release is 7.0.0-rc.0 from 2 October, a release candidate for testnet only; its notes say mainnet operators are not required to upgrade. A pull request adding the mainnet height to Zebra (#11830) was opened at 22:52 UTC on 20 October and was still open this morning. The Zakura node, a Zebra fork, moved faster: it merged the height at 02:02 UTC on 21 October and published 1.7.0-rc2 at 04:27 UTC, the first node build that schedules NU7 on mainnet. It is still marked as a pre-release. Zebra’s readiness tracker for mainnet (issue #11674, last updated at 14:29 UTC on 20 October) still listed open sync-stall fixes, several without an owner, three private security fixes, and about 14 of 31 peer groups ready on testnet against a 75% target. The older zcashd node is deprecated and its last release, 6.20.0, dates from June.
Zebra 6.4.0, released on 23 September, cut its own end-of-support height to around 2 November “in preparation for NU7”, with a note that the next Zebra release should support the upgrade. Versions 6.4.0 and 6.4.1 were later withdrawn over a denial-of-service flaw in the handling of malformed version 6 transactions, and Zebra asks operators to run 6.4.2, released on 25 September. Nodes on the 6.4 line will stop on their own a few days before the new rules start.
When does NU7 activate? Around 5 to 6 November, by our estimate
No official calendar date came with the height. The schedule that Bowe posted on the NU7 Timeline thread of the community forum on 17 September set testnet activation for 6 October, the final mainnet decision for 20 October and mainnet activation for 5 November. He described the plan as agreed unanimously by the Zcash Foundation, Project Tachyon, Valar Group, ZODL, Shielded Labs and the Zakura and Zebra teams.
Our estimate starts from the chain tip. Blockchair showed block 3,525,254 at 06:31 UTC on 21 October, 18,151 blocks short of the target. At the current target of 75 seconds a block, that is about 15.8 days, which lands around 00:40 UTC on Friday 6 November. Blocks have run slightly fast lately (1,159 in the past 24 hours against 1,152 expected), so a late 5 November arrival is just as plausible. Treat any exact hour as an estimate until block explorers start counting down.
What NU7 changes: 25-second blocks, a fee reserve and the end of version 4
ZIP 259 lists what the upgrade switches on. It shortens the block target spacing from 75 to 25 seconds (ZIP 218), adds limits on shielded actions per pool and per block, creates the Network Sustainability Mechanism (ZIP 237), removes 60% of fees from circulation (ZIP 235), invalidates version 4 transactions (ZIP 2003) and changes a funding-stream address (ZIP 2008). The document states plainly that NU7 does not deploy ZIP 233 or ZIP 234, two earlier fee and issuance proposals that some coverage still mentions. There is no new transaction format, and the 21 million ZEC cap stays.
The new consensus branch ID is 0x77190AD9, and mainnet nodes need protocol version 170190 to stay connected.
| Parameter | Before NU7 | After NU7 (from block 3,543,405) |
|---|---|---|
| Target time between blocks | 75 seconds | 25 seconds |
| Block subsidy (current halving period) | 1.5625 ZEC | 0.52083333 ZEC |
| New ZEC per day | about 1,800 | about 1,800 |
| Blocks between halvings | 1,680,000 | 5,040,000 |
| Share of fees kept by the miner | 100% | 40% (60% to the reserve) |
| Difficulty averaging window | 17 blocks | 102 blocks |
| Default wallet expiry | 40 blocks (about 50 min) | 120 blocks (about 50 min) |
| Coinbase maturity | 100 blocks (about 125 min) | 100 blocks (about 42 min) |
| Maximum reorg length | 99 blocks | at least 600 blocks (about 4.2 h) |
| Version 4 transactions | valid | invalid |
Source: ZIP 259, ZIP 218 and pull request #1405; daily issuance and durations are Coindaro calculations.
Why faster blocks
ZIP 218, written by Dev Ojha and Evan Forbes of Valar Group, argues that one confirmation in 25 seconds on average helps point-of-sale payments, exchange deposits and cross-chain bridges. It names NEAR Intents among the services that wait for only one or two confirmations. We covered how ZEC swaps through NEAR Intents work and the trail they leave earlier this week. The ZIP says it does not argue for clients cutting their confirmation counts, and expects users who keep comparable policies to wait less than today.
The authors claim a 37% improvement in worst-case wallet sync from the new action limits and, for simple two-action transactions, more than double the throughput of Ironwood, the shielded pool added in July, in the short term. The cost is about 200 kB a day of extra block headers for every wallet.
What changes for miners and issuance
For miners the arithmetic is simple. In the current halving period the block subsidy, which miners share with the development funding streams, is 1.5625 ZEC; after NU7 it is 52,083,333 zatoshis, or 0.52083333 ZEC. With three times as many blocks, that comes to the same 1,800 ZEC a day by our count. Rounding shaves about half a ZEC off total future issuance over the whole schedule, by the formula in ZIP 218.
Halvings keep their place on the calendar. The halving interval triples to 5,040,000 blocks, and the third halving now sits at block 6,132,390, which at 25 seconds a block falls around late November 2028 by our estimate. The subsidy then drops to 0.26041666 ZEC per block. Readers new to the idea can start with our explainer on how halvings cut new supply; Zcash copied Bitcoin’s four-year rhythm.
Fees change more in principle than in money. Under ZIP 235, owned by Shielded Labs and Eiger developers, 60% of every transaction fee leaves circulation and 40% goes to the miner as before. The removed ZEC goes into a balance tracked by the Network Sustainability Mechanism of ZIP 237. From block 8,939,664, about mid-February 2031 on our estimate, each block pays out a fixed fraction of that balance, calibrated so that half of it is reissued in every four-year halving period. The balance is seeded at NU7 with 368.58 ZEC of rewards and fees that miners left unclaimed before NU6, so it is above zero from the first block.
Today the amounts are small. Blockchair put the median fee over the past 24 hours at 10,000 zatoshis at 06:31 UTC on 21 October, or 0.0001 ZEC, about 13 cents at that price. Removing 60% of that is mostly a statement of intent for now.
Pools also have technical homework. Zebra 7’s getblocktemplate leaves only the time field editable, so pools must request fresh templates rather than reuse old ones. Coinbase rewards still need 100 blocks to mature, which now means roughly 42 minutes instead of about two hours. The difficulty adjustment looks back over 102 blocks instead of 17. The funding streams for Zcash Community Grants and the protocol lockbox are extended to the new third-halving height.
How coinholders voted, and where the experts disagreed
The fee design came out of two polls in late summer. The coinholder poll weighted votes by ZEC. About 2.4 million ZEC took part, well over the 1 million ZEC threshold; to count, coins had to sit in the Ironwood shielded pool at block 3,459,350 on 24 August. On whether to keep the four-year halvings or smooth issuance instead, 2,375,932 ZEC (98.9%) chose halvings. On when reissuance should start, 2,319,644 ZEC (96.6%) picked February 2031, against 70,240 for as soon as possible and 6,283 for February 2027, according to the results Bowe posted on 14 September. The other answers were just as lopsided: 2,333,855 ZEC backed disabling version 4 transactions at NU7, and 2,397,669 ZEC backed 25-second blocks against 142 ZEC opposed.
The ZCAP panel, which gives one vote per member, leaned the other way. Of 198 members, 135 voted, the Zcash Foundation reported; a summary posted in the results thread puts the issuance question at 57 for smoothing and 54 for keeping halvings. On 15 September Shielded Labs, Project Tachyon, ZODL, the Zcash Foundation and Valar Group settled on February 2031 as the most conservative reading. ZIP 259 itself records that the polls did not reach a shared majority position on when reissuance should begin.
Testnet: NU7 has been running since 4 October
The upgrade activated on testnet at block 4,465,026 on 4 October, two days ahead of plan. An independent count posted on the forum on 18 October by a user named PulseHawk, covering 49,203 blocks, found a mean block time of 23.68 seconds and a median of 17 seconds, close to the expected 17.3. The longest gap was 451 seconds. Of six hashrate jumps of two times or more, five were absorbed, with difficulty back within 15% of the new level after a median of 960 blocks, about 160 minutes. During a 330-minute listening window, 5 of 780 announced blocks did not end up in the chain, each one block deep. Thirty consecutive NU7 blocks spanned a median of 730 seconds, about what ten blocks take at the old pace. Those are one observer’s numbers, not an official audit.
The same poster wrote in a 20 October thread that “Exchanges and wallets that count blocks rather than time will need new numbers.” Sync stalls reported on testnet since the release candidate are part of the open work on Zebra’s tracker.
The risk the developers accepted: old nodes on a dead chain
Zcash normally leaves a safety margin. Under ZIP 200, an upgrade activates only after the last software that does not support it has passed its end-of-support height, and about three months after the first supporting release. For NU7 alone, ZIP 259 waives both rules. Operators of unsupported software may stay online at activation and follow the old consensus branch, the document says, and announcements must warn them to upgrade first.
Zebra’s 6.4 line is covered by its own stop height around 2 November. The exposure is any other old software, or any operator who misses the stable release when it comes, with less than three weeks left and no stable build out yet.
Sprout freeze and what wallets and exchanges must do before the height
ZIP 2003, owned by Hopwood, makes every version 4 transaction invalid from NU7. That includes transparent-only and Sapling transactions built in the old format, as well as Sprout ones. Versions 5 and 6 carry on. Sprout funds can only be spent in a version 4 transaction, so whatever sits in the pool becomes unspendable at the height. The coins are not burned, and a future upgrade could in theory restore access, but nothing of the kind is planned.
The pool is small. The Cipherscan explorer showed 22,263 ZEC in Sprout at about 06:30 UTC on 21 October, roughly $28 million at $1,257 and 0.13% of the supply. Blockhead had counted about 22,309 ZEC on 17 October, so only a few dozen coins left the pool in four days. The only maintained software with Sprout wallet functions was zcashd, now deprecated. Cointelegraph reported the warning on 23 September after Zooko Wilcox shared it on X.
ZEC holders
ZEC on an exchange, or in a wallet using Transparent, Sapling, Orchard or Ironwood addresses through version 5 or 6 transactions, needs no action beyond updating the wallet app. Anyone still holding Sprout funds, on addresses that start with zc, has to move them out before block 3,543,405. NU7 creates no new coin and no fork token: there is nothing to claim.
Exchange users
Expect pauses. When the previous upgrade, NU6.3, went live in July, Cobo suspended ZEC deposits and withdrawals from 04:00 UTC on 28 July until the network was judged stable. No exchange had published an NU7 notice by the morning of 21 October. Gemini moved to the Zakura node on 29 September and said deposits and withdrawals would work as before. Each platform sets its own confirmation count. On testnet, 30 NU7 blocks took about as long as 10 blocks at the old pace, so a platform that wants the same waiting time would count roughly three times as many; one that keeps its count will simply credit deposits sooner. Liquidity on cross-chain routes is a separate story: THORChain’s ZEC trading was still halted on 19 October after a bug slashed 18 of its nodes.
Miners, pools and node operators
Zebra operators should be on 6.4.2 now and move to a stable Zebra 7.0.0 carrying the mainnet height once it is out; the 6.4 line stops around 2 November either way. Zakura 1.7.0-rc2 already schedules NU7 at block 3,543,405 but is a pre-release, and the last stable Zakura, 1.6.0 from 1 October, does not include the mainnet height. After activation, NU7 nodes drop peers that advertise a protocol version below 170190. Zebra 7 migrates its database to version 29, so back up the version 28 database first; the Zallet wallet and Zaino indexer backends must be upgraded at the same time. Indexers, explorers and light-wallet servers are affected too.
Wallet developers and users
Wallets must stop building version 4 transactions for anything that could be mined after activation. That also applies to saved and offline-signed transactions, and ZIP 259 warns that re-signing alone cannot make a version 4 transaction valid. Because signatures commit to the branch ID, even version 5 or 6 transactions signed before activation may fail after it. Default expiry moves to 120 blocks, the same 50 minutes or so. Bowe wrote on 17 September that the change should not affect wallets in any significant way, though a developer reported on 13 October that an unmodified build of the WebZjs web wallet library could not sync on the NU7 testnet. Hardware wallet readiness was not confirmed in anything we read.
What NU7 does not change, and the next dates
NU7 touches speed, fees and old formats. It leaves Zcash’s privacy features as they are, so the long-run question for European users stays the same: under Article 79 of the EU anti-money-laundering regulation (Regulation (EU) 2024/1624), crypto-asset service providers may not keep accounts that allow transactions to be anonymised or obscured, including through anonymity-enhancing coins, from 10 July 2027. Our Zcash (ZEC) coin page covers the shielded pools and that rule in more detail.
Before activation, watch for the merge of pull request #1405, the move of the NU7 ZIPs to Proposed status, stable releases of Zebra 7.0.0 and Zakura 1.7.0, and exchange notices on deposit pauses. Then comes block 3,543,405, due around 5 or 6 November.