diff --git a/source/packages/plg_system_mokosuiteauto/src/Helper/TradeInHelper.php b/source/packages/plg_system_mokosuiteauto/src/Helper/TradeInHelper.php
new file mode 100644
index 0000000..e87d6aa
--- /dev/null
+++ b/source/packages/plg_system_mokosuiteauto/src/Helper/TradeInHelper.php
@@ -0,0 +1,90 @@
+<?php
+namespace Moko\Plugin\System\MokoSuiteAuto\Helper;
+
+defined('_JEXEC') or die;
+
+use Joomla\CMS\Factory;
+use Joomla\Database\DatabaseInterface;
+
+/**
+ * Trade-in appraisal — valuation, condition assessment, equity calculation.
+ */
+class TradeInHelper
+{
+	/**
+	 * Submit a trade-in appraisal.
+	 */
+	public static function submitAppraisal(string $vin, int $ownerContactId, int $mileage, string $condition, float $appraisalValue): object
+	{
+		$allowedConditions = ['excellent', 'good', 'fair', 'poor'];
+		if (!in_array($condition, $allowedConditions, true)) {
+			$condition = 'fair';
+		}
+
+		if ($appraisalValue < 0) {
+			throw new \InvalidArgumentException('Appraisal value cannot be negative.');
+		}
+
+		$db = Factory::getContainer()->get(DatabaseInterface::class);
+
+		$tradeIn = (object) [
+			'vin'              => strtoupper($vin),
+			'owner_contact_id' => $ownerContactId,
+			'mileage'          => max(0, $mileage),
+			'vehicle_condition'=> $condition,
+			'appraisal_value'  => round($appraisalValue, 2),
+			'status'           => 'pending_review',
+			'appraised_by'     => (int) Factory::getApplication()->getIdentity()->id,
+			'appraised_at'     => Factory::getDate()->toSql(),
+		];
+
+		$db->insertObject('#__mokosuiteauto_trade_ins', $tradeIn, 'id');
+
+		return (object) ['success' => true, 'trade_in_id' => (int) $tradeIn->id];
+	}
+
+	/**
+	 * Calculate trade equity (trade value minus payoff).
+	 */
+	public static function calculateEquity(int $tradeInId): object
+	{
+		$db = Factory::getContainer()->get(DatabaseInterface::class);
+
+		$db->setQuery($db->getQuery(true)
+			->select('ti.appraisal_value, ti.payoff_amount')
+			->from($db->quoteName('#__mokosuiteauto_trade_ins', 'ti'))
+			->where('ti.id = ' . (int) $tradeInId));
+		$ti = $db->loadObject();
+
+		if (!$ti) {
+			return (object) ['success' => false, 'error' => 'Trade-in not found'];
+		}
+
+		$equity = (float) $ti->appraisal_value - (float) ($ti->payoff_amount ?? 0);
+
+		return (object) [
+			'trade_in_id'     => $tradeInId,
+			'appraisal_value' => (float) $ti->appraisal_value,
+			'payoff_amount'   => (float) ($ti->payoff_amount ?? 0),
+			'equity'          => round($equity, 2),
+			'is_negative'     => $equity < 0,
+		];
+	}
+
+	/**
+	 * Get pending trade-in appraisals needing manager review.
+	 */
+	public static function getPendingReview(): array
+	{
+		$db = Factory::getContainer()->get(DatabaseInterface::class);
+
+		$db->setQuery($db->getQuery(true)
+			->select('ti.*, cd.name AS owner_name, cd.telephone')
+			->from($db->quoteName('#__mokosuiteauto_trade_ins', 'ti'))
+			->join('LEFT', $db->quoteName('#__contact_details', 'cd') . ' ON cd.id = ti.owner_contact_id')
+			->where($db->quoteName('ti.status') . ' = ' . $db->quote('pending_review'))
+			->order('ti.appraised_at ASC'));
+
+		return $db->loadObjectList() ?: [];
+	}
+}