Zcash NU7 Update Will Triple Block Speed and Change Fees

The Zcash network is preparing for the NU7 upgrade, which will reduce the target block interval from 75 to 25 seconds and change the fee distribution. The new rules will take effect at block number 3,543,405. As of November 5, the upgrade has not yet been activated. The estimated timeframe is November 6 UTC, but the exact time depends on the block formation speed.

After the transition, the network will aim for approximately 3,456 blocks per day instead of 1,152. This will allow for faster transaction confirmations, but does not guarantee the same reduction in the time it takes for ZEC to be credited to exchanges. Platforms set their own required number of confirmations and conduct additional checks. For example, with the unchanged requirement of six confirmations, the estimated time to form six blocks will decrease from 7.5 to 2.5 minutes.

For working with shielded transactions, NU7 also introduces load limits on individual blocks. These are designed to ease wallet synchronization and increase the estimated throughput of certain operations. The actual number of transactions will depend on user activity.

How Fees and Access to Sprout Will Change

Due to the threefold increase in the number of blocks, the subsidy per block will decrease by approximately 67%. However, the planned daily issuance of ZEC will remain the same, as will the maximum supply of 21 million coins.

Under the new rules, miners will be able to receive 40% of the total transaction fees in a block. The remaining 60% will be temporarily removed from circulation into the network's sustainability reserve. Additional rewards from this reserve will start being distributed from block number 8,939,664. This does not involve the permanent destruction of coins: the funds are intended to be reissued according to protocol rules.

Another change will affect the outdated shielded pool Sprout. NU7 will stop accepting version 4 transactions, which allow spending funds in it. After activation, the remaining ZEC in Sprout will become unavailable for transfers even with keys. They will not be destroyed, but restoring the ability to use them would require a separate change to the network rules, which is not guaranteed.

The restriction specifically affects funds in Sprout, not all Zcash wallets. Holders of such balances need to check the possibility of transferring them before activation. Node operators are also provided with a transition to compatible software before the new rules take effect.