diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index 5222874..ca0ec84 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -802,15 +802,25 @@ CalcState CALCULATE_LIBRARY_API compute_duration_for_parking_ticket(
     if (start.isValid()) {
         QString cs = start.toString(Qt::ISODate);
 
+        bool prepaid = true;
+        int paymentOptionIndex = tariff->getPaymentOptionIndex(permitType);
+        int prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
+        if (prepaid_option_id == 2) { // see tariff03.json for 502: 2 means no prepaid-option
+            prepaid = false;
+        }
+        bool const nextDay = false;
+
         // DEBUG
-        qCritical() << "compute_duration_for_parking_ticket(): ";
-        qCritical() << "      start (cs): " << cs;
-        qCritical() << "           price: " << price;
+        qCritical() << "compute_duration_for_parking_ticket(1): ";
+        qCritical() << " payment option index: " << paymentOptionIndex;
+        qCritical() << "              prepaid: " << prepaid;
+        qCritical() << "           start (cs): " << cs;
+        qCritical() << "                price: " << price;
 
         duration = Calculator::GetInstance().GetDurationFromCost(tariff,
-                                                  tariff->getPaymentOptions().pop_payment_method_id,
+                                                  tariff->getPaymentOptions(paymentOptionIndex).pop_payment_method_id,
                                                   cs.toLocal8Bit().constData(),
-                                                  price, false, true).c_str();
+                                                  price, permitType, nextDay, prepaid).c_str();
         QDateTime d = QDateTime::fromString(duration, Qt::ISODate);
         if (!d.isValid()) {
             calcState.setDesc(QString("ticketEndTime=%1").arg(duration));
@@ -831,13 +841,28 @@ CalcState CALCULATE_LIBRARY_API compute_duration_for_parking_ticket(
         PermitType permitType)
 {
     CalcState calcState;
+
+    bool prepaid = true;
+    int paymentOptionIndex = tariff->getPaymentOptionIndex(permitType);
+    int prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
+    if (prepaid_option_id == 2) {
+        prepaid = false;
+    }
+    bool const nextDay = false;
+
+    // DEBUG
+    qCritical() << "compute_duration_for_parking_ticket(2): ";
+    qCritical() << " payment option index: " << paymentOptionIndex;
+    qCritical() << "              prepaid: " << prepaid;
+    qCritical() << "                price: " << price;
+
     if (start_parking_time.isValid()) {
         QString cs = start_parking_time.toString(Qt::ISODate);
         QString endTime = Calculator::GetInstance().GetDurationFromCost(
                     tariff,
                     tariff->getPaymentOptions().pop_payment_method_id,
                     cs.toLocal8Bit().constData(),
-                    price, permitType, false, true).c_str();
+                    price, permitType, nextDay, prepaid).c_str();
 
         if (endTime == CalcState::SUCCESS) {
             calcState.setDesc(QString("SUCCESS"));