Staking withdrawals
Enabling withdrawals
For your validator to be capable of withdrawals of any kind, a withdrawal address must be provided and registered to your account on the Beacon Chain. This should be an address you control, and cannot be changed once set.Current validators
Depending how you set up your initial deposit, your account may or may not be ready for withdrawals already:- Staking Deposit CLI: if you used the “eth1 withdrawal address” (--eth1_withdrawal_address) flag when generating your keys, you're good to go
- Wagyu Key Gen GUI: if you provided a withdrawal address when generating your keys, you're good to go (found under “advanced mode”)
How to update validator keys
If your validator account still has BLS withdrawal credentials (0x00), a one-time message must be broadcast signaling which execution layer account should be used for all withdrawals.- 0x00 = "Type 0" = BLS keys = Old withdrawal credentials: Not eligible for withdrawals
- 0x01 = "Type 1" = Execution keys = New withdrawal credentials: Withdrawals enabled
Tools available for generating key change message
- Staking Deposit CLI - Launchpad walkthrough tutorial
- ethdo - Changing withdrawal credentials
This requires use of your mnemonic seed phrase, and should be performed on an offline air-gapped machine.
BLS To Execution Change (BTEC) queue
BLS withdrawal credentials (0x00) can be updated to an execution address (0x01) by broadcasting a BLS To Execution Change (BTEC) message, signed with your BLS withdrawal key. These messages are included in blocks at a max rate of 16 per block.If more than 16 requests are being made at one time, a queue will be formed and these will be processed in subsequent blocks. Once completed, your validator is permanently enabled for withdrawals, and will be eligible for payouts during the next sweep.Excess balance withdrawals (partial withdrawals)
An excess balance withdrawal is processed when an active validator has a maxed out effective balance of 3 ETH, and has a total balance over 3 ETH. A single validator cannot get rewards on excess balance over 3 ETH, and thus these accounts will have any extra balance automatically withdrawn to their Ethereum address.These are also referred to as “partial withdrawals” or “reward payments” as the remaining 3 ETH stays locked and staked.📝 It is not possible to manually request specific amounts of ETH to be withdrawn
How to exit from staking (full withdrawals)
A full withdrawal is processed for any inactivated validators that are no longer considered to be staking, that have fully exited from their validation responsibilities. Thus for a validator to fully withdraw its balance, it must first complete the process of exiting.To exit staking and fully withdrawal your entire remaining balance, you must do two things:
- Make sure you’ve updated your withdrawal credentials with an execution withdrawal address
- Signal your intent to exit staking by signing and broadcasting a voluntary exit message to the network using your validator keys and validator client
- Exiting a Lighthouse validator
- Exiting a Lodestar validator
- Exiting a Nimbus validator
- Exiting a Prysm validator
- Exiting a Teku validator
- Anyone wishing to conclude their staking obligations can sign a “voluntary exit” message which is then broadcast to the Beacon Chain to start the process. This is a manual step.
- Accounts that have been slashed, or have insufficient balance, will be forced to exit according to the network rules. This is automatic and cannot be stopped once initiated.
📝 Validators still need to complete their validation duties until they are exited
Mechanics of withdrawals: How they work
Withdrawals as an operation, not a new transaction type
Ethereum users are used to transactions being executed in a manual way—if you want to transfer funds, you have to sign a transaction and pay the gas.EIP-4895, titled Beacon chain push withdrawals as operations, implements a design that simplified this whole process for stakers.Instead of a new transaction type being used for stakers to manually request withdrawals, accounts are automatically checked for eligible excess balance every few days. All validators are checked on an endless loop, and any available rewards or exited funds are automatically “pushed” into a provided withdrawal account.Withdrawal queue
The withdrawal queue is automatically filled and processed by block proposers, who automatically check for any available payouts via a sweeping mechanism.On a never-ending loop, every single validator account is continuously evaluated for eligible ETH withdrawals (of which there are two types, more on this below). Validators are processed in order by index number, originally starting at 0, with each subsequent proposer picking up where the last one left off.When a validator is scheduled to propose the next block, it performs a sweep of validator accounts looking for eligible withdrawals. During the sweep, the validator will check a max of 16,384 accounts, attempting to find 16 available withdrawals to be processed in the next block.Like a clock hand, this process progresses in one direction, and when the last validator is reached, the sweep starts over again from the beginning. At each validator along the way, the account is evaluated for potential withdrawals.📝Note the “withdrawal” and “BLS To Execution Change” queues are independent and do not compete. Each are limited on a per-block basis.
Exit queue and activation queue
As anyone who has already gone through the process of activating a validator knows, this process is not automatic, especially if there are a lot of other users trying to join at the same time. This is because the consensus layer uses an activation queue to limit how quickly new validator accounts can join the network.Similarly, there is also an exit queue, which limits how quickly validators can leave the network. This is for security reasons. Given each validator is limited to a max effective balance of 3 ETH, this prevents large portions of the ETH from potentially being used in an attack and then quickly exiting from the network all at once.The number of validators that can be activated or exited in a given epoch (6.4 minutes) is determined by how many active validators are currently on the network.Four (4) validator exits are allowed per epoch, plus one (1) more for every 65,536 total active validators over 327,680. As of April 2023 this limit is eight (8), and will increase to nine (9) if/when the active validator count reaches 655,360.📝Note the “activation” and “exit” queues are independent and do not compete. Each are limited on a per-epoch basis.
Exit epoch and withdrawable epoch
Immediately upon broadcasting a signed voluntary exit message, the exit epoch and withdrawable epoch values are calculated based off the current epoch number. These values determine exactly when the validator will no longer be required to be online performing validation, and when the validator is eligible for a full withdrawal respectively.- At least ~25 minutes (four epochs) from the current epoch before reaching the exit epoch (with no others in the queue, highly variable)
- Then another ~27 hours (256 epochs) before those funds are flagged as withdrawable
- Then up to a few more days for the next validator sweep to execute the full withdrawal (assumes 0x01 withdrawal credentials)
Note that once a user has 0x01 withdrawal credentials and has broadcast a voluntary exit, there is no further action required until the processing is complete.
How each validator is evaluated for withdrawals
A decision tree is followed to determine what type of withdrawal will be initiated. If the validator being checked has ETH that is eligible to be withdrawn, it is added to the withdrawal queue. If there isn’t, the account is skipped.- Has a withdrawal address been provided?
- If so, move to next question
- If not, stop. No withdrawal will be processed and account skipped
- Has the validator completed the exiting process?
- If so, stop. Full withdrawal processed for any remaining balance
- If not, move to next question
- Is the effective balance maxed out at 3 ETH?
- If so, excess balance withdrawal processed
- If not, no withdrawal will be processed and account skipped
What factors affect the frequency of payouts?
How long the cycle takes to check every account depends on:- Rate-limits set on withdrawal queue
- Max withdrawals per payload: 16 (24)
Maximum number of withdrawals that can be processed in a single block - Max validators per withdrawals sweep: 16,384 (214)
Maximum number of accounts that can be checked in a block. Stops when 16 withdrawals are found. If 16 eligible rewards are not found in the first 16,384 accounts checked, the withdrawal queue for that block will be submitted as is, and the following proposer will pick up where this left off.
- Max withdrawals per payload: 16 (24)
- Total number of validator accounts (index count, every validator account ever registered, up-only over time)
- Total number of validator accounts that have eligible withdrawals (variable)
- Accounts without updated withdrawal credentials will be skipped
- Accounts that have fully withdrawn and have a zero balance will be skipped
- Active accounts with an effective balance or total balance less than 3 ETH will be skipped
- Number of empty slots (missed block opportunities, variable, typically minimal)
- Consensus layer slot timing: 12 seconds (no plans to change)
| Number of withdrawals | Time to complete |
|---|---|
| 400,000 | 3.5 days |
| 500,000 | 4.3 days |
| 600,000 | 5.2 days |
| 700,000 | 6.1 days |
| 800,000 | 7 days |