# Make an ACF End Date Come After the Start Date

> Blocks saving when an end date field is earlier than its start date field, such as for events, offers or bookings.

- Type: PHP
- Runs: Run everywhere
- Category: [Custom Post Types & Fields](https://wpide.com/library/category/post-types/)
- Tags: acf, validation, dates
- Author: WPIDE Team
- Installs: 0
- Updated: 2026-10-28
- Page: https://wpide.com/library/acf-validate-end-after-start/

## Code

```php
// End date field name, and the start date field's key.
$wpide_acf_end_field = 'end_date';
$wpide_acf_start_key = 'field_start_date';

add_filter( 'acf/validate_value/name=' . $wpide_acf_end_field, function ( $valid, $value ) use ( $wpide_acf_start_key ) {
    if ( true !== $valid || '' === (string) $value || empty( $_POST['acf'][ $wpide_acf_start_key ] ) ) { // phpcs:ignore WordPress.Security.NonceVerification -- ACF verifies its own nonce.
        return $valid;
    }

    $start = sanitize_text_field( wp_unslash( $_POST['acf'][ $wpide_acf_start_key ] ) ); // phpcs:ignore WordPress.Security.NonceVerification

    // ACF date and date-time pickers submit sortable values (Ymd or Y-m-d H:i:s).
    if ( strtotime( (string) $value ) < strtotime( $start ) ) {
        return 'The end date must be on or after the start date.';
    }

    return $valid;
}, 10, 2 );
```

## Notes

Set the field names and the start field's key (shown under each field when "Field Keys" is ticked in Screen Options).

## How to use it

Install the free WPIDE plugin (https://wordpress.org/plugins/wpide/), find "Make an ACF End Date Come After the Start Date" in its snippet library and add it in one click; or create a new PHP snippet in WPIDE (or any code snippets plugin) and paste the code above. More snippets: https://wpide.com/library/