diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index 43e228c..b56ee49 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -97,11 +97,31 @@ void CALCULATE_LIBRARY_API free_tariff(parking_tariff_t *tariff) {
 // UpDown 1 -> up; 0 -> down
 int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int currentTimeMinutes, int UpDown)
 {
+    Configuration const *cfg = tariff;
+
+    // compute payment method id (e.g. Linear=3, Steps=4)
+    PaymentMethod const paymentMethodId = Utilities::getPaymentMethodId(cfg);
+    switch (paymentMethodId) {
+    case PaymentMethod::Progressive:
+        qCritical() << "   compute_next_timestep() paymentMethodId: Progressive";
+        break;
+    case PaymentMethod::Degressive:
+        qCritical() << "   compute_next_timestep() paymentMethodId: Degressive";
+        break;
+    case PaymentMethod::Linear:
+        qCritical() << "   compute_next_timestep() paymentMethodId: Linear";
+        break;
+    case PaymentMethod::Steps:
+        qCritical() << "   compute_next_timestep() paymentMethodId: Steps";
+        break;
+    case PaymentMethod::Undefined:
+        qCritical() << "   compute_next_timestep() paymentMethodId: Undefined";
+        break;
+    }
+
     // use tariff with structure as for instance Schnau, Koenigsee:
     // without given YearPeriod, SpecialDays and SpecialDaysWorktime
-    if (tariff->YearPeriod.size() == 0
-        && tariff->SpecialDays.size() == 0
-        && tariff->SpecialDaysWorktime.size() == 0)
+    if (paymentMethodId == PaymentMethod::Steps)
     {
         static const QList<int> stepList = calculator.GetTimeSteps(tariff);
 
@@ -130,8 +150,8 @@ int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int cu
                 return stepList[currentStepIndex - 1];
             }
         }
-    } else {
-        Configuration const *cfg = tariff;
+    } else
+    if (paymentMethodId == PaymentMethod::Linear) {
 
         // currentTimeMinutes is the number of minutes actually used. This
         // value is an offset from the start time and cannot be used as a
@@ -139,9 +159,6 @@ int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int cu
 
         qCritical() << "compute_next_timestep() currentTimeMinutes:" << currentTimeMinutes;
 
-        // compute payment method id (e.g. Linear=3, Steps=4)
-        PaymentMethod paymentMethodId = Utilities::getPaymentMethodId(cfg);
-        qCritical() << "   compute_next_timestep() paymentMethodId:" << paymentMethodId;
 
         // get minimal and maximal parking times
         int const minParkingTime = Utilities::getMinimalParkingTime(cfg, paymentMethodId);