# Registration burn (/docs/guides/mining/burn)

Every subnet charges a single floating **registration price**, read live with
[`burn`](/docs/query/burn). What happens to your payment is set by the
subnet's [`collateral_lock_share`](/docs/hyperparameters/collateral-lock-share)
(call it `p`):

* the `(1 − p)` share is **burned** — sunk, never refunded;
* the `p` share is **locked as collateral** — stake you earn back by mining,
  covered in [registration collateral](/docs/guides/mining/collateral).

With `p = 0` (the chain default) the whole price is burned, which is the
classic burned registration this page describes. Everything here about how
the price moves applies identically on collateral subnets — only the split
of the payment changes.

## How the price floats [#how-the-price-floats]

Admission is governed entirely by price, with no registration windows:

* The price **decays over time**
  ([`update_registration_prices_for_networks`](/code/pallets/subtensor/src/subnets/registration.rs#L489-L531)),
  halving every [`burn_half_life`](/code/pallets/subtensor/src/lib.rs#L2778)
  blocks (default 360, about one tempo; owner-settable).
* Each successful registration **multiplies the price**
  ([`bump_registration_price_after_registration`](/code/pallets/subtensor/src/subnets/registration.rs#L533-L557))
  by [`burn_increase_mult`](/code/pallets/subtensor/src/lib.rs#L2783)
  (default 1.26), so a registration rush gets expensive fast.
* The price is clamped between
  [`min_burn`](/docs/hyperparameters/min-burn) (default 500,000 rao =
  τ0.0005) and [`max_burn`](/docs/hyperparameters/max-burn) (default 100
  TAO). All are per-subnet hyperparameters.

<RegistrationBurnTimeline />

The result is price discovery: the price settles where the marginal
registrant's willingness to pay meets supply. A miner who expects a
registration slot to return `X` is willing to pay up to `X` for it, and the
decay/bump dynamics float the price to that level. An idle subnet rests at
exactly `min_burn`.

## What the burned share buys (and where it goes) [#what-the-burned-share-buys-and-where-it-goes]

The burned TAO is **recycled, not staked** — deregistering does not refund
it. Under the hood
([`do_register`](/code/pallets/subtensor/src/subnets/registration.rs#L110-L125)),
the TAO is swapped into the subnet's pool and the resulting alpha is removed
from the subnet's outstanding supply.

Economically, the burn is the subnet's spam throttle. It prices the
*registration event itself*: every attempt costs it, no matter how the
attempt turns out, which is what keeps registration races and UID-lottery
spam expensive. What the burn cannot do is price *behavior after
registration* — a registered miner has nothing left at stake. That gap is
what [collateral](/docs/guides/mining/collateral) exists to fill.

## Worked example [#worked-example]

Suppose netuid 42 has `min_burn` = τ0.5, `burn_increase_mult` = 1.26,
`burn_half_life` = 360, and the price is currently τ1.00 with no collateral
configured (`p = 0`):

1. You register and pay τ1.00. All of it is burned. The price immediately
   jumps to τ1.26 for the next registrant.
2. Two more miners register in the same tempo: they pay τ1.26 and τ1.59.
   The price is now τ2.00.
3. Nobody registers for the next 360 blocks: the price decays back to
   τ1.00, and after another 360 quiet blocks it would rest at min\_burn's
   clamp path (τ0.5 floor).

Your τ1.00 is gone regardless of what happens next — if you are pruned in a
week, re-registering costs whatever the price is then.

## Owner controls [#owner-controls]

All owner-settable through `btcli sudo set` (rate-limited, and only outside
the subnet's weights window):

```bash
btcli sudo set --netuid 42 --name min_burn --value 500000000        # rao
btcli sudo set --netuid 42 --name max_burn --value 100000000000     # rao
btcli sudo set --netuid 42 --name burn_half_life --value 360        # blocks
btcli sudo set --netuid 42 --name burn_increase_mult --value 1.26
```

* [`min_burn`](/docs/hyperparameters/min-burn) — the resting price of an
  idle subnet; keeps registration from becoming free. On collateral subnets
  this floors the *total* price, of which only `(1 − p)` is burned.
* [`max_burn`](/docs/hyperparameters/max-burn) — ceiling during registration
  rushes.
* [`burn_half_life`](/docs/hyperparameters/burn-half-life) — how fast the
  price cools; shorter half-life means cheaper re-entry after a rush.
* [`burn_increase_mult`](/docs/hyperparameters/burn-increase-mult) — how
  hard each registration pushes the price up; higher values throttle rushes
  more aggressively.

## Related [#related]

[Registration collateral](/docs/guides/mining/collateral),
[`collateral_lock_share`](/docs/hyperparameters/collateral-lock-share),
[`burn` query](/docs/query/burn),
[`burned-register`](/docs/tx/burned-register)