# Create a Time-Based Upkeep
Source: https://docs.chain.link/chainlink-automation/guides/job-scheduler

> For the complete documentation index, see [llms.txt](/llms.txt).

Create powerful automation for your smart contract using time schedules without having to create Automation-compatible contracts. This guide explains how to register time-based upkeeps.

(Image: Job Scheduler animation)

> **TIP: Testing and best practices**
>
> Follow the [best practices](/chainlink-automation/concepts/best-practice) when creating an Automation-compatible
> contract and test your upkeep on a testnet before deploying it to a mainnet.

> **CAUTION: Upgrade Time-Based Upkeep Recommended**
>
> The Automation “Time-based” upkeep contract has been updated so that only the unique forwarder for your upkeep can call it. If your upkeep was deployed before 11 December 2025, we recommend you replace your existing “Time-based” upkeeps using the new “Time-based” upkeep.

To upgrade, simply follow the [Automation UI](https://automation.chain.link/) to register a new “Time-based” upkeep with the same details as your previous upkeep. Once registered, you can delete the previous upkeep.

Upgrading to the latest “Time-based” upkeep removes i) the ability of 3rd parties to trigger your upkeep, and ii) the possibility that a call with insufficient gas ticks the Timer forward but fails to execute your desired function.

## Using the Chainlink Automation app

In the [Chainlink Automation App](https://automation.chain.link/), click the blue **Register new Upkeep** button.

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### Connecting your wallet

If you do not already have a wallet connected with the Chainlink Automation network, the interface will prompt you to do so. Click the **Connect Wallet** button and follow the remaining prompts to connect your wallet to one of the [Automation supported blockchain networks](/chainlink-automation/overview/supported-networks).

(Image: Image)

## Trigger selection

Select **Time-based** trigger.

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## Using time-based triggers

When you select the time-based trigger, you are prompted to enter a *contract address*. Provide the address of the contract you want to automate. If you did not verify the contract on chain, you will need to paste the [Application Binary Interface](https://docs.soliditylang.org/en/develop/abi-spec.html) (ABI) of the deployed contract into the corresponding text box. Select the function name that you want to execute and provide any static inputs. If you want to use dynamic inputs please see [Custom logic Upkeeps](/chainlink-automation/guides/register-upkeep)

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### Specifying the time schedule

After you have successfully entered your contract address and ABI, specify your time schedule in the form of a [CRON expression](https://en.wikipedia.org/wiki/Cron). CRON expressions provide a shorthand way of creating a time schedule. You can use the provided example buttons in the Automation app to experiment with different schedules. Then, create your own time schedule.

```
Cron jobs are interpreted according to this format:

  ┌───────────── minute (0 - 59)
  │ ┌───────────── hour (0 - 23)
  │ │ ┌───────────── day of the month (1 - 31)
  │ │ │ ┌───────────── month (1 - 12)
  │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday)
  │ │ │ │ │
  │ │ │ │ │
  │ │ │ │ │
  * * * * *

All times are in UTC.

- can be used for range e.g. "0 8-16 * * *"
/ can be used for interval e.g. "0 */2 * * *"
, can be used for list e.g. "0 17 * * 0,2,4"

Special limitations:
  * there is no year field
  * no special characters: ? L W #
  * lists can have a max length of 26
  * no words like JAN / FEB or MON / TUES
```

After entering your CRON expression, click **Next**.

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## Entering upkeep details

Provide the following information in the Automation app:

- **Upkeep name**: This will be visible in the Chainlink Automation app.
- **Gas limit**: This is the maximum amount of gas that your transaction requires to execute on chain. This limit cannot exceed the `performGasLimit` value configured on the [registry](/chainlink-automation/overview/supported-networks).

> **NOTE: Job Scheduler Gas requirements**
>
> When you create an upkeep through the Job Scheduler, Chainlink Automation deploys a new `CronUpkeep` contract from the
> [CronUpkeepFactory](https://github.com/smartcontractkit/chainlink/blob/d5a253fb6959104844eda8479c08909a76a6fea7/contracts/src/v0.8/automation/upkeeps/CronUpkeepFactory.sol)
> to manage your time schedule and ensure that it is compatible. Because this contract uses roughly 110K gas per call, it is
> recommended to add 150K additional gas to the gas limit of the function you would like to automate.

- **Starting balance (LINK)**: Specify a LINK starting balance to fund your upkeep. See the [LINK Token Contracts](/resources/link-token-contracts) page to find the correct contract address and access faucets for testnet LINK. This field is required. You must have LINK before you can use the Chainlink Automation service.

> **TIP: ERC-677 Link**
>
> For registration you must use ERC-677 LINK. Read our [LINK](/resources/link-token-contracts) page to determine where
> to acquire mainnet LINK, or visit [faucets.chain.link](https://faucets.chain.link/) to request testnet LINK.

- **Your email address (optional)**: This email address will be used to send you an email notification when your upkeep is underfunded.

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## Complete upkeep registration

Click **Register upkeep** and confirm the transaction in MetaMask.
(Image: Upkeep Registration Success Message)

Your upkeeps will be displayed in your list of **Active Upkeeps**. You must monitor the balance of your upkeep. If the balance drops below the **minimum balance**, the Chainlink Automation Network will not perform the Upkeep. See [Managing Upkeeps](/chainlink-automation/guides/manage-upkeeps) to learn how to manage your upkeeps.