# Expire At a Specific Time

In this guide, you'll learn how you can configure a Grant Kit to automatically revoke access to a grant after some date. You'll do this by importing and using an expiration policy Abbey provides out-of-the-box.

We will be using the [expire-after-a-duration](https://docs.abbey.io/use-cases/time-based-access/expire-after-a-duration "mention") guide as a base and modify it to this use case.

## Step 1: Configure Your Policy

Write your policy using Abbey's expiration helper functions.

{% code title="common.rego" lineNumbers="true" %}

```rego
package common

import data.abbey.functions

allow[msg] {
  functions.expire_at("2023-06-15T04:00:00+00:00")
  msg := "granting access funtil 06/15/2023 4am UTC."
}
```

{% endcode %}

Unlike the `functions.expire_after` helper which uses a duration, the `functions.expire_at` takes an RFC 3339 datetime string.

{% hint style="info" %}
Abbey revokes grants in realtime. When the date and time is reached, the grant will be revoked immediately.
{% endhint %}