burn
Call v205 → current #10Burns TAO from the caller, permanently reducing total issuance .
View calls on chainCall Workflow
This diagram shows the call execution flow: starting with burn, passing through validation
(signature, nonce, mortality, fee payment), then pre-dispatch checks, followed by dispatch which emits events: Burned and modifies storage: TotalIssuance, and finally post-dispatch where ExtrinsicSuccess is emitted and fees are settled.
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Used by: developersvalidators
The Big Picture
Unlike sending to a burn address (which just makes funds inaccessible), this actually reduces TotalIssuance. The tokens are permanently destroyed, not just locked.
Use Cases
- Deflationary mechanisms
- Destroying unwanted tokens
- Token economics experiments
From Chain Metadata
Burn the specified liquid free balance from the origin account. If the origin's account ends up below the existential deposit as a result of the burn and `keep_alive` is false, the account will be reaped. Unlike sending funds to a _burn_ address, which merely makes the funds inaccessible, this `burn` operation will reduce total issuance by the amount _burned_.
Input Parameters
| # | Name | Type | Description |
|---|---|---|---|
| 0 | value | Compact<u64> Cpt T::Balance | value: Balance in chain native currency (RAO for TAO; ÷10⁹) (RAO -> TAO (/ 10^9)) |
| 1 | keep_alive | bool | keep_alive (bool) |
Permissions
Origin
Unknown
Required Role
Permission data inferred from metadata. May be incomplete.
Requirements
- Caller has sufficient free balance
- If keep_alive is true, caller must retain existential deposit
Effects
Events Emitted
Storage Modified
Postconditions
- Caller balance decreased by burn amount
- TotalIssuance decreased by burn amount
- Burned event emitted
Side Effects
- May reap caller account if balance falls below ED and keep_alive is false
- Permanently removes TAO from circulation
Code Examples
import { createClient, Binary } from "polkadot-api";
import { getWsProvider } from "polkadot-api/ws";
import { sub } from "@polkadot-api/descriptors"; // generated by: npx papi add sub -w wss://entrypoint-finney.opentensor.ai:443
const client = createClient(getWsProvider("wss://entrypoint-finney.opentensor.ai:443"));
const api = client.getTypedApi(sub);
// Build burn call (typed, named args)
const value = 0n;
const keep_alive = true;
const tx = api.tx.Balances.burn({
value,
keep_alive,
});Runtime Info
- Pallet Index
- 5
- Call Index
- 10
- First Version
- v205
- Current Version
- v411