# Tax Exemption Checkbox With Certificate Number

> Adds an "I am tax exempt" checkbox and certificate number to the classic checkout; when ticked, tax is removed and the number is saved on the order.

- Type: PHP
- Runs: Run everywhere
- Category: [WooCommerce](https://wpide.com/library/category/woocommerce/)
- Requires: WooCommerce
- Tags: woocommerce, tax, checkout, b2b
- Author: WPIDE Team
- Installs: 0
- Updated: 2026-10-28
- Page: https://wpide.com/library/woo-tax-exempt-checkbox/

## Code

```php
add_filter( 'woocommerce_checkout_fields', function ( $fields ) {
    $fields['billing']['billing_tax_exempt'] = array(
        'type'     => 'checkbox',
        'label'    => 'I am tax exempt',
        'class'    => array( 'form-row-wide', 'update_totals_on_change' ),
        'priority' => 125,
    );
    $fields['billing']['billing_tax_exempt_id'] = array(
        'type'     => 'text',
        'label'    => 'Tax exemption certificate number',
        'class'    => array( 'form-row-wide' ),
        'priority' => 126,
    );

    return $fields;
} );

add_action( 'woocommerce_checkout_update_order_review', function ( $post_data ) {
    parse_str( (string) $post_data, $posted );
    WC()->customer->set_is_vat_exempt( ! empty( $posted['billing_tax_exempt'] ) );
} );

add_action( 'woocommerce_after_checkout_validation', function ( $data, $errors ) {
    if ( ! empty( $data['billing_tax_exempt'] ) && '' === trim( (string) ( $data['billing_tax_exempt_id'] ?? '' ) ) ) {
        $errors->add( 'validation', 'Please enter your tax exemption certificate number.' );
    }
}, 10, 2 );

add_action( 'woocommerce_checkout_process', function () {
    if ( WC()->customer ) {
        WC()->customer->set_is_vat_exempt( ! empty( $_POST['billing_tax_exempt'] ) ); // phpcs:ignore WordPress.Security.NonceVerification
    }
} );
```

## Notes

The snippet only checks that a certificate number was entered, so verify numbers before you ship.

## How to use it

Install the free WPIDE plugin (https://wordpress.org/plugins/wpide/), find "Tax Exemption Checkbox With Certificate Number" 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/