# set-crowdloan-max-contribution (/docs/tx/set-crowdloan-max-contribution)

Caps how much any single contributor can put in, useful to keep a raise
broadly distributed. Omitting the amount clears the limit. Only the
creator may change it, and only while the loan has not been finalized.

| Signer    | Origin                                 | Pallet    | Wraps                                                                            |
| --------- | -------------------------------------- | --------- | -------------------------------------------------------------------------------- |
| `coldkey` | signed account (pallet role may apply) | Crowdloan | [`Crowdloan.set_max_contribution`](/code/pallets/crowdloan/src/lib.rs#L933-L967) |

## Parameters [#parameters]

| Parameter                  | Type              | Required | Description                                                               |
| -------------------------- | ----------------- | -------- | ------------------------------------------------------------------------- |
| `crowdloan_id`             | integer           | yes      | Identifier of the crowdloan, assigned when it was created.                |
| `new_max_contribution_tao` | number \| `"all"` | no       | Largest total any single contributor may put in. Omit to clear the limit. |

Address parameters (`--hotkey`, `--coldkey`, `--dest`, ...) accept a raw ss58
address, an address-book or proxy-book name, or a local wallet/hotkey name.

## CLI [#cli]

Preview with `--dry-run` (shows fee, effects, and policy result without
submitting), then submit:

```bash
btcli tx set-crowdloan-max-contribution \
  --crowdloan-id <int> --dry-run
btcli tx set-crowdloan-max-contribution \
  --crowdloan-id <int> -w my_coldkey
```

## Python [#python]

```python
import bittensor as bt
from bittensor.wallet import Wallet

wallet = Wallet(name="my_coldkey", hotkey="my_hotkey")
intent = bt.SetCrowdloanMaxContribution(crowdloan_id=0)

sub = bt.Subtensor()
plan = sub.plan(intent, wallet)   # fee, effects, policy — no submission
result = sub.execute(intent, wallet)
if not result.success:
    print(result.error.code, result.error.remediation)
```

(`bt.Subtensor` is also the async client — `async with bt.Subtensor() as client:`
— see [The client](/docs/concepts/client).) Or build the intent by op name, as
an agent would:

```python
result = sub.execute_tool("set_crowdloan_max_contribution", {...}, wallet)
```

## On-chain implementation [#on-chain-implementation]

`Crowdloan.set_max_contribution` — [`pallets/crowdloan/src/lib.rs#L935`](/code/pallets/crowdloan/src/lib.rs#L933-L967):

```rust
#[pallet::call_index(9)]
#[pallet::weight(T::WeightInfo::set_max_contribution())]
pub fn set_max_contribution(
    origin: OriginFor<T>,
    #[pallet::compact] crowdloan_id: CrowdloanId,
    new_max_contribution: Option<BalanceOf<T>>,
) -> DispatchResult {
    let who = ensure_signed(origin)?;

    let crowdloan = Self::ensure_crowdloan_exists(crowdloan_id)?;
    ensure!(!crowdloan.finalized, Error::<T>::AlreadyFinalized);

    // Only the creator can update the max contribution.
    ensure!(who == crowdloan.creator, Error::<T>::InvalidOrigin);

    if let Some(max_contribution) = new_max_contribution {
        let creator_contribution =
            Contributions::<T>::get(crowdloan_id, &crowdloan.creator)
                .unwrap_or_else(Zero::zero);
        ensure!(
            max_contribution >= crowdloan.min_contribution
                && max_contribution >= creator_contribution,
            Error::<T>::MaximumContributionTooLow
        );
        MaxContributions::<T>::insert(crowdloan_id, max_contribution);
    } else {
        MaxContributions::<T>::remove(crowdloan_id);
    }

    Self::deposit_event(Event::<T>::MaxContributionUpdated {
        crowdloan_id,
        new_max_contribution,
    });
    Ok(())
}
```

Every file is browsable under [/code](/code) exactly as built into the runtime, or as plain text under `/code/raw/<path>` (index: [`/code/index.json`](/code/index.json)).