diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index 935b872..b54fabd 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -929,6 +929,25 @@ CalcState CALCULATE_LIBRARY_API compute_duration_for_parking_ticket(
     }
 
     if (start_parking_time.isValid()) {
+
+        // handle prepaid option
+        QDateTime effectiveStartTime(start_parking_time);
+        int const prepaid_option_id = tariff->getPaymentOptions(paymentOptionIndex).pop_prepaid_option_id;
+        std::optional<ATBPrepaid> prepaidOption = tariff->getPrepaidType(prepaid_option_id);
+        if (prepaidOption.has_value()) {
+            ATBPrepaid const &p = prepaidOption.value();
+            if (p.never) {
+                qCritical() << __func__ << __LINE__ << "prepaid: no";
+            } else {
+                if (start_parking_time.time() < p.static_end) {     // static_end: e.g. 08:00:00
+                    effectiveStartTime.setTime(p.static_end);
+                } else
+                if (start_parking_time.time() > p.static_start) {   // static_start: e.g. 22:00:00
+                    effectiveStartTime.setTime(p.static_start);
+                }
+            }
+        }
+
         QString cs = start_parking_time.toString(Qt::ISODate);
         QString endTime = Calculator::GetInstance().GetDurationFromCost(
                     tariff,