The Zcash network is set to activate its next major upgrade, NU7, at block 3,543,405 on November 5, 2026. This network-wide change will make all funds remaining in the legacy Sprout privacy pool unspendable, directly impacting holders with balances in this earlier privacy option.
Sprout funds to be locked permanently
According to on-chain data, approximately 12,224 ZEC, equal to about $15 million to $16 million at recent prices near $1,230 per coin, still resides in the Sprout pool. Once NU7 is activated, ZEC holders who have not migrated their funds from Sprout will lose the ability to transfer or spend those coins, even though their private keys remain unchanged. The unspent coins will remain on the blockchain but cannot be moved as the consensus rules will no longer accept version-4 (v4) transactions used by Sprout.
ZIP 2003 clarifies that while Sprout funds remain technically part of the total supply, “holders should treat remaining Sprout funds as practically locked once NU7 activates,” since a future upgrade may or may not restore access to these coins.
A block height-based activation means the real-time activation is expected near 9:30 p.m. Eastern, but the rule triggers at the designated block, not an exact time.
Mini dictionary: Sprout pool – The original privacy pool in Zcash allowing users to shield transaction details, superseded by newer pools like Sapling and Orchard for improved security and performance.
Technical details of NU7: new rules and faster blocks
NU7, according to the Zcash Improvement Proposals ZIP 2003 and ZIP 259, will disallow all v4 transactions associated with Sprout. Only newer formats such as v5 and v6 will remain valid for moving funds. This rule is enforced at the network level, rather than as an optional wallet setting, and cannot be bypassed by users.
As a result, Sapling, Orchard, and transparent ZEC can still be spent or transferred as usual under the permitted transaction formats. The Sprout balance itself is not deleted or burned; it continues to represent issued supply, but spending paths are effectively closed unless a future upgrade re-enables access.
Alongside the privacy changes, NU7 introduces a major technical enhancement—reducing the target block interval from 75 seconds to 25 seconds. This increases the network’s speed substantially with blocks arriving three times as quickly. The time required for three confirmations will drop from roughly 3.75 minutes to about 75 seconds.
| Feature | Before NU7 | After NU7 |
|---|---|---|
| Sprout pool spendability | Spendable | Not spendable |
| Target block interval | 75 seconds | 25 seconds |
| Transaction confirmation (3 blocks) | 3.75 minutes | 75 seconds |
| ZEC supply cap | 21 million | 21 million |
| Sprout coins affected | ≈12,224 ZEC | Locked |
While the total ZEC cap of 21 million coins and the four-year halving schedule remain unchanged, the more frequent blocks will lower the per-block subsidy, keeping daily issuance broadly stable.
Transaction fees and the Network Sustainability Mechanism
With NU7, ZIP 235 establishes new fee rules. Sixty percent of transaction fees will be redirected into the Network Sustainability Mechanism (NSM), with miners retaining the remaining forty percent. The NSM is designed to help fund ongoing development and maintenance of the network.
Planned reissuance from the NSM is scheduled for approximately block 8,939,664, which is expected to occur in 2031 based on the mainnet timeline.
Mini dictionary: Network Sustainability Mechanism (NSM) – A Zcash protocol feature that accumulates a portion of transaction fees in a reserve, later reissued to support the project’s long-term development and sustainability.
The upcoming NU7 upgrade represents one of Zcash’s most significant protocol changes in recent years. While the main focus remains on privacy enhancements and streamlining transaction formats, the network’s faster operations and updated fee model are also expected to reshape user experience and miner incentives.
