# collateral_drain_ratio (/docs/hyperparameters/collateral-drain-ratio)

`collateral_drain_ratio` (call it `k`) sets how fast a hotkey earns back the
collateral locked at registration when the subnet uses a nonzero
[`collateral_lock_share`](/docs/hyperparameters/collateral-lock-share).
Operators care because `lock / k` is the total emission (miner incentive and
validator dividends) they must earn before their collateral is fully
withdrawable; owners tune it to control how long hotkeys stay collateralized
— the security parameter for subnets whose scoring can be gamed on short
horizons.

## How it works [#how-it-works]

Each tempo, when hotkey emission is credited
([`distribute_dividends_and_incentives`](/code/pallets/subtensor/src/coinbase/run_coinbase.rs#L669-L766)
in `pallets/subtensor/src/coinbase/run_coinbase.rs`),
[`settle_miner_collateral`](/code/pallets/subtensor/src/subnets/collateral.rs#L193-L229)
releases

```
released = min(locked − min_locked, k × emission)
```

from the hotkey's lock back to withdrawable stake, where `min_locked` is the
optional self-maintained floor (zero unless set via `set_min_collateral`;
while the lock is under the floor, emission is captured into the lock
instead). The release is keyed to the registered hotkey even when miner
incentive is redirected by auto-stake. At `k = 1` (the default) collateral
releases one-for-one with earned emission; at `k = 0.5` a hotkey must earn
two alpha per alpha released; at `k = 2` half the lock's worth of emission
releases all of it.

The subnet value is stored in
[`CollateralDrainRatio`](/code/pallets/subtensor/src/lib.rs#L2795-L2801) as a
`U64F64` fixed-point number, but each miner's effective ratio is **snapshot
into their collateral entry at registration**
([`MinerCollateralState`](/code/pallets/subtensor/src/lib.rs#L364-L383)):
owner changes apply to future registrations only and can never slow (or
speed) the drain of standing collateral. The owner-set extrinsic
([`sudo_set_collateral_drain_ratio`](/code/pallets/admin-utils/src/lib.rs#L2311-L2354)
in `pallets/admin-utils/src/lib.rs`) requires `0 < k ≤ 10`
([`MaxCollateralDrainRatio`](/code/pallets/subtensor/src/lib.rs#L446-L450));
out-of-range values fail with
[`CollateralDrainRatioOutOfBounds`](/docs/errors/chain/CollateralDrainRatioOutOfBounds).
Zero is excluded by design: with no exit path for collateral, `k = 0` would
make the lock permanently unrecoverable — a burn with extra steps.

The deterrence math, briefly: an adversary who plans to farm emissions and
abandon the hotkey must collect roughly `T / (1 + k)` (T = registration
price) before validators stop scoring them, just to break even. Lower `k`
raises that bar; see the
[worked example](/docs/guides/mining/collateral#a-subnet-deters-tail-risk-farming).

## Reading and setting [#reading-and-setting]

```
btcli sudo get --netuid N --name collateral_drain_ratio
```

Fixed-point decimal; owner or root, rate-limited, outside the weights window:

```
btcli sudo set --netuid N --name collateral_drain_ratio --value 0.5
```

Common settings: 1.0 (default, earn-back at par), 0.2–0.5 (slow release for
long-horizon or gameable-score subnets), 2.0 (fast release where the entry
gate matters more than ongoing lockup).

## Related [#related]

[`collateral_lock_share`](/docs/hyperparameters/collateral-lock-share),
[`burn_half_life`](/docs/hyperparameters/burn-half-life),
[Registration collateral guide](/docs/guides/mining/collateral)