diff --git a/library/src/calculate_price.cpp b/library/src/calculate_price.cpp
index 347d6ce..938f379 100644
--- a/library/src/calculate_price.cpp
+++ b/library/src/calculate_price.cpp
@@ -372,8 +372,31 @@ int CALCULATE_LIBRARY_API compute_next_timestep(parking_tariff_t *tariff, int cu
         // progressive tariff: e.g. Neuhauser, Kirchdorf (743)
         (paymentMethodId == PaymentMethod::Progressive))
     {
-        const QList<int> stepList = Calculator::GetInstance().GetTimeSteps(tariff);
-        qCritical() << "   compute_next_timestep()     timeSteps:" << stepList;
+        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;
+        }
+
+        qCritical() << "   compute_next_timestep()      first time step:" << stepList[0];
+        qCritical() << "   compute_next_timestep()            timeSteps:" << stepList;
+        qCritical() << "   compute_next_timestep() currentTimeInMinutes:" << currentTimeMinutes;
+
+        // 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);