diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index b2aa2fc..938f379 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -344,7 +344,7 @@ int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int cu
     qCritical() << "   compute_next_timestep()     currentTimeMinutes: " << currentTimeMinutes;
     qCritical() << "   compute_next_timestep() up/down (1=up, 0=down): " << UpDown;
 
-    Configuration *cfg = tariff;
+    Configuration const *cfg = tariff;
 
     // compute payment method id (e.g. Linear=3, Steps=4)
     PaymentMethod const paymentMethodId = Utilities::getPaymentMethodId(cfg);
@@ -372,71 +372,39 @@ int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int cu
         // progressive tariff: e.g. Neuhauser, Kirchdorf (743)
         (paymentMethodId == PaymentMethod::Progressive))
     {
-        QVector<QList<int>> stepListVec;
-        QList<int> const timeSteps = Calculator::GetInstance().GetTimeSteps(tariff);
-
-        qCritical() << "   compute_next_timestep() time-steps: " << timeSteps;
-
-        int paymentOptionIndex = 0;
-        int const pop_time_step_config = tariff->getPaymentOptions(paymentOptionIndex).pop_time_step_config;
-
-        if (pop_time_step_config == (int)ATBTimeStepConfig::TimeStepConfig::DYNAMIC) {
-            QList<int> lst;
-            for (int index = 0; index < 5; ++index) {
-                lst.clear();
-                QListIterator<int> i(timeSteps);
-                while (i.hasNext()) {
-                    switch (index) {
-                    case 0:
-                        lst.append(i.next());
-                    break;
-                    case 1:
-                        lst.append(i.next() - 2);
-                    break;
-                    case 2:
-                        lst.append(i.next() - 1);
-                    break;
-                    case 3:
-                        lst.append(i.next() + 1);
-                    break;
-                    case 4:
-                        lst.append(i.next() + 2);
-                    break;
-                    default:;
-                    }
-                }
-                qCritical() << "   compute_next_timestep() " << index << "list of time-steps" << lst;
-                stepListVec.append(lst);
-            }
-        }
-
-        int stepListIndex = -1;
-
-        for (int index = 0; index < stepListVec.size(); ++index) {
-            if (stepListVec[index].indexOf(currentTimeMinutes) != -1) {
-                stepListIndex = index;
-                break;
-            }
-        }
-
-        if (stepListIndex == -1) {
-            qCritical() << "compute_next_timestep() *NO STEP INDEX* for currentTimeMinutes (" << currentTimeMinutes << ")";
+        QList<int> &stepList = Calculator::GetInstance().GetTimeSteps(tariff);
+        int const size = stepList.size();
+        if (size == 0) {
+            qCritical() << "compute_next_timestep() *ERROR empty step-list*";
             return  currentTimeMinutes;
         }
 
-        QList<int> const &stepList = stepListVec[stepListIndex];
-        qCritical() << "   compute_next_timestep()         index:" << stepListIndex;
-        qCritical() << "   compute_next_timestep()     timeSteps:" << stepList;
+        qCritical() << "   compute_next_timestep()      first time step:" << stepList[0];
+        qCritical() << "   compute_next_timestep()            timeSteps:" << stepList;
+        qCritical() << "   compute_next_timestep() currentTimeInMinutes:" << currentTimeMinutes;
 
-        int const currentStepIndex = stepList.indexOf(currentTimeMinutes); // must be currentStepIndex != -1
+        // consider time shift: the step-list might have been computed at a
+        // slightly different time point
+        int maxStep = -1;
+        if (size >= 2) {
+            maxStep = stepList[1] - stepList[0];
+        }
+        int tolerance = (maxStep == -1) ? 5 : std::min(maxStep, 5);
+        if (std::abs(stepList[0] - currentTimeMinutes) <= tolerance) {
+            qCritical().noquote()
+                << QString("   compute_next_timestep() correction stepList[0]=%1 -> %2:")
+                                    .arg(stepList[0]).arg(currentTimeMinutes);
+            stepList[0] = currentTimeMinutes;
+            qCritical() << "   compute_next_timestep()        NEW timeSteps:" << stepList;
+        }
+
+        int currentStepIndex = stepList.indexOf(currentTimeMinutes);
 
         if (currentStepIndex == -1) {
             qCritical() << "compute_next_timestep() *NO STEP* for currentTimeMinutes (" << currentTimeMinutes << ")";
             return  currentTimeMinutes;
         }
 
-        cfg->getPaymentOptions(paymentOptionIndex).pop_min_time = stepList.first();
-
         if (UpDown == 1) { // UP
             if (stepList[currentStepIndex] == stepList.last()) {
                 qCritical() << "compute_next_timestep() *NO NEXT STEP* for currentTimeMinutes (" << currentTimeMinutes << ")";