diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index 9df6563..166bd31 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -145,6 +145,14 @@ std::string Calculator::GetDurationFromCost(Configuration* cfg,
     qCritical() << DBG_HEADER << "     time steps:" << tsteps;
 
     if (paymentMethodId == PaymentMethod::Degressive) {
+
+        if (static_cast<int>(cost) < cfg->getPaymentOptions(paymentOptionIndex).pop_min_price) {
+            // minimal price is set by GetTimeSteps()
+            qCritical() << DBG_HEADER << "   provided price (cost):" << cost;
+            qCritical() << DBG_HEADER << "configured minimal price:" << cfg->getPaymentOptions(paymentOptionIndex).pop_min_price;
+            return CalcState::BELOW_MIN_PARKING_PRICE.toStdString();
+        }
+
         if (prepaid == false) {
             int const pop_id = cfg->getPaymentOptions(paymentOptionIndex).pop_id;
             int const pop_accumulate_prices = cfg->getPaymentOptions(paymentOptionIndex).pop_accumulate_prices;