Magento : Create Tax Rules and Tax Class Programmatically with installer

createTaxClassInstaller.php

<?php
/**
 * This file is part of Namespace_Tax for Magento.
 *
 * @license http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 * @author Phuong LE <[email protected]> <AgenceSoon>
 * @category Namespace
 * @package Namespace_Tax
 * @copyright Copyright (c) 2017 Agence-Soon (http://www.agence-soon.fr)
 */

try {

    /** @var Mage_Tax_Model_Class $taxClassModel */
    $taxClassModel = Mage::getModel('tax/class');
    $taxClassModel->setClassName('Professionnels');
    $taxClassModel->setClassType(Mage_Tax_Model_Class::TAX_CLASS_TYPE_CUSTOMER);
    $taxClassModel->save();

} catch (Exception $e) {
    // Silence is golden
    Mage::logException($e);
    if (Mage::getIsDeveloperMode()) {
        Mage::throwException($e->getMessage());
    }
}

createTaxRulesInstaller.php

<?php
/**
 * This file is part of Namespace_Tax for Magento.
 *
 * @license http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 * @author Phuong LE <[email protected]> <AgenceSoon>
 * @category Namespace
 * @package Namespace_Tax
 * @copyright Copyright (c) 2017 Agence-Soon (http://www.agence-soon.fr)
 */

try {

    /** @var Mage_Tax_Model_Calculation_Rate $taxCalculationRateModel */
    $taxCalculationRateModel = Mage::getModel('tax/calculation_rate');
    $taxRate20 = $taxCalculationRateModel->loadByCode('FR - 20%');

    /**
     * List our rules code
     */
    $rulesCode = [
        "Professionnels - CE - 20% - 20",
        "Professionnels - CE - 20% - 10",
        "Professionnels - CE - 20% - 5.5"
    ];

    /**
     * List our Tax Class Name Type Product
     * You must create your tax class first
     */
    $taxClassNameTypeProduct = [
        'Biens et services soumis à la TVA à 20%',
        'Biens et services soumis à la TVA à 10%',
        'Biens et services soumis à la TVA à 5,5%'
    ];

    /** @var Mage_Tax_Model_Class $taxClassModel */
    $taxClassModel = Mage::getModel('tax/class');

    $model= clone($taxClassModel);
  
    /** Here you need to create your "Professionnels" Tax Class before */
    $model->load('Professionnels', 'class_name');
    $proClassNameId = $model->getId();

    $classNameId = [];

    foreach ($taxClassNameTypeProduct as $name) {
        $model = clone($taxClassModel);
        $model->load($name, 'class_name');
        $classNameId[] = $model->getId();
    }


    /** @var Mage_Tax_Model_Calculation_Rule $taxRuleModel */
    $taxRuleModel = Mage::getModel('tax/calculation_rule');

    $i = 0;
    foreach ($rulesCode as $code) {
        $model = clone($taxRuleModel);
        $data = [
            'code' => $code,
            'tax_rate' => [$taxRate20->getId()],
            'tax_customer_class' => [$proClassNameId],
            'tax_product_class' => [$classNameId[$i]],
            'priority' => "0",
            'position' => "0"
        ];

        $model->setData($data);
        $model->save();
        $i++;
    }
  
  /**
   * Result : Here we will apply a tax rate 20% for each product if the customer is a Professional
   */

} catch (Exception $e) {
    // Silence is golden
    Mage::logException($e);
    if (Mage::getIsDeveloperMode()) {
        Mage::throwException($e->getMessage());
    }
}