> ## Documentation Index
> Fetch the complete documentation index at: https://docs.base.org/llms.txt
> Use this file to discover all available pages before exploring further.
# Spend Permissions
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### Structs
#### `SpendPermission`
Defines the complete parameters of a spend permission.
The fields of the `SpendPermission` structure must be strictly ordered as
defined below.
| Field | Type | Description |
| ----------- | --------- | ------------------------------------------------------------------------------------------ |
| `account` | `address` | Smart account this spend permission is valid for. |
| `spender` | `address` | Entity that can spend `account`'s tokens. |
| `token` | `address` | Token address (ERC-7528 native token address or ERC-20 contract). |
| `allowance` | `uint160` | Maximum allowed value to spend within each `period`. |
| `period` | `uint48` | Time duration for resetting used `allowance` on a recurring basis (seconds). |
| `start` | `uint48` | Timestamp this spend permission is valid starting at (unix seconds). |
| `end` | `uint48` | Timestamp this spend permission is valid until (unix seconds). |
| `salt` | `uint256` | An arbitrary salt to differentiate unique spend permissions with otherwise identical data. |
| `extraData` | `bytes` | Arbitrary data to include in the permission. |
#### `PeriodSpend`
Describes the cumulative spend for the current active period.
| Field | Type | Description |
| ------- | --------- | ---------------------------------------- |
| `start` | `uint48` | Start time of the period (unix seconds). |
| `end` | `uint48` | End time of the period (unix seconds). |
| `spend` | `uint160` | Accumulated spend amount for period. |
***
### Contract functions
#### `approve`
Approve a spend permission via a direct call from the `account`. Only callable by the `account` specified in the spend permission.
```solidity theme={null}
function approve(SpendPermission calldata spendPermission) external;
```
***
#### `approveWithSignature`
Approve a spend permission via a signature from the `account` owner. Compatible with [ERC-6492](https://eips.ethereum.org/EIPS/eip-6492) signatures for automatic account creation if needed.
```solidity theme={null}
function approveWithSignature(SpendPermission calldata spendPermission, bytes calldata signature) external;
```
***
#### `spend`
Spend tokens using a spend permission, transferring them from the `account` to the `spender`. Only callable by the `spender` specified in the permission.
```solidity theme={null}
function spend(SpendPermission memory spendPermission, uint160 value) external;
```
***
#### `revoke`
Revoke a spend permission, permanently disabling its use. Only callable by the `account` specified in the spend permission.
```solidity theme={null}
function revoke(SpendPermission calldata spendPermission) external;
```
***
#### `revokeAsSpender`
Revoke a spend permission, permanently disabling its use. Only callable by the `spender` specified in the spend permission.
```solidity theme={null}
function revokeAsSpender(SpendPermission calldata spendPermission) external;
```
***
#### `getHash`
Generate a hash of a `SpendPermission` struct for signing, in accordance with [EIP-712](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md).
```solidity theme={null}
function getHash(SpendPermission memory spendPermission) public view returns (bytes32);
```
***
#### `isApproved`
Check if a spend permission is approved, regardless of whether the current time is within the valid time range of the permission.
```solidity theme={null}
function isApproved(SpendPermission memory spendPermission) public view returns (bool);
```
***
#### `isRevoked`
Check if a spend permission is revoked, regardless of whether the current time is within the valid time range of the permission.
```solidity theme={null}
function isRevoked(SpendPermission memory spendPermission) public view returns (bool);
```
***
#### `isValid`
Check if a spend permission is approved and not revoked, regardless of whether the current time is within the valid time range of the permission.
```solidity theme={null}
function isValid(SpendPermission memory spendPermission) public view returns (bool);
```
***
#### `getLastUpdatedPeriod`
Retrieve the `start`, `end`, and accumulated `spend` for the last updated period of a spend permission.
```solidity theme={null}
function getLastUpdatedPeriod(SpendPermission memory spendPermission) public view returns (PeriodSpend memory);
```
***
#### `getCurrentPeriod`
Retrieve the `start`, `end`, and accumulated `spend` for the current period of a spend permission.
Reverts if the current time is outside the valid time range of the permission, but does not validate whether the
spend permission has been approved or revoked.
```solidity theme={null}
function getCurrentPeriod(SpendPermission memory spendPermission) public view returns (PeriodSpend memory);
```