Форум

\Bitrix\Main\Loader::includeModule('sale');
$sCoupon = 'discount_5';
\Bitrix\Sale\DiscountCouponsManager::add($sCoupon);
$oBasket = \Bitrix\Sale\Basket::loadItemsForFUser(
    \Bitrix\Sale\Fuser::getId(),
    \Bitrix\Main\Context::getCurrent()->getSite()
);
$oDiscounts = \Bitrix\Sale\Discount::loadByBasket($oBasket);
$oBasket->refreshData([ 'PRICE' ,  'COUPONS']);
$oDiscounts->calculate();
$result = $oDiscounts->getApplyResult();
echo '<pre>', mydump($result), '</pre>';