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add_filter( 'woocommerce_checkout_fields', 'reorder_woo_fields' );
 
function reorder_woo_fields( $fields ) {
	//move these around in the order you'd like
	$fields2['billing']['billing_first_name'] = $fields['billing']['billing_first_name'];
	$fields2['billing']['billing_last_name']  = $fields['billing']['billing_last_name'];
	$fields2['billing']['billing_company']    = $fields['billing']['billing_company'];
	$fields2['billing']['billing_address_1']  = $fields['billing']['billing_address_1'];
	$fields2['billing']['billing_address_2']  = $fields['billing']['billing_address_2'];
	$fields2['billing']['billing_city']       = $fields['billing']['billing_city'];
	$fields2['billing']['billing_postcode']   = $fields['billing']['billing_postcode'];
	$fields2['billing']['billing_state']      = $fields['billing']['billing_state'];
	$fields2['billing']['billing_country']    = $fields['billing']['billing_country'];
	$fields2['billing']['billing_email']      = $fields['billing']['billing_email'];
	$fields2['billing']['billing_phone']      = $fields['billing']['billing_phone'];
 
	//just copying these (keeps the standard order)
	$fields2['shipping'] = $fields['shipping'];
	$fields2['account']  = $fields['account'];
	$fields2['order']    = $fields['order'];
 
	return $fields2;
}