diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index 6995743..6c223fe 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -695,72 +695,86 @@ Ticket Calculator::private_GetDurationFromCost(Configuration *cfg,
                cost, Ticket::s[VALID]);
 }
 
-QList<int> Calculator::GetTimeSteps(Configuration *cfg) const {
-    QList<int> timeSteps;
+QList<int> Calculator::GetTimeSteps(Configuration *cfg, quint64 startInMinutes) const {
+    static QList<int> timeSteps;
 
-    int const pop_id = cfg->getPaymentOptions().pop_id;
-    int const pop_carry_over = cfg->getPaymentOptions().pop_carry_over;
-    int const pop_time_step_config = cfg->getPaymentOptions().pop_time_step_config;
+    if (timeSteps.size() == 0) {
+        int const pop_id = cfg->getPaymentOptions().pop_id;
+        int const pop_carry_over = cfg->getPaymentOptions().pop_carry_over;
+        int const pop_time_step_config = cfg->getPaymentOptions().pop_time_step_config;
 
-    if (pop_time_step_config == (int)ATBTimeStepConfig::TimeStepConfig::DYNAMIC) {
-        if (pop_carry_over) {
-            int const pop_carry_over_time_range_id = cfg->getPaymentOptions().pop_carry_over_time_range_id;
-            QTime const carryOverTimeRangeFrom = cfg->TimeRange.find(pop_carry_over_time_range_id)->second.time_range_from;
-            QTime const carryOverTimeRangeTo = cfg->TimeRange.find(pop_carry_over_time_range_id)->second.time_range_to;
+        qCritical() << "              payment option id:" << pop_id;
+        qCritical() << "      payment option carry over:" << pop_carry_over;
+        qCritical() << "payment option time step config:" << pop_time_step_config;
 
-            if (carryOverTimeRangeFrom.secsTo(carryOverTimeRangeTo) <= 60) { // carry over time point, usually 00:00:00
-                if (carryOverTimeRangeFrom == QTime(0, 0, 0)) {
-                    for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr) {
-                        int const durationId = itr->second.pra_payment_unit_id;
-                        auto search = cfg->Duration.find(durationId);
-                        if (search != cfg->Duration.end()) {
-                            ATBDuration duration = search->second;
-                            if (durationId == 1) {
-                                //duration.pun_duration_min = search->second.pun_duration_min;
-                                //duration.pun_duration_max = search->second.pun_duration_max;
+        if (pop_time_step_config == (int)ATBTimeStepConfig::TimeStepConfig::DYNAMIC) {
+            QDateTime start;
+            start.setSecsSinceEpoch(startInMinutes * 60);
+            uint16_t timeStepCompensation = 0;
 
-                                QDateTime carryOver = m_start;
-                                carryOver = carryOver.addDays(1);
-                                carryOver.setTime(QTime(0, 0, 0));
+            if (pop_carry_over) {
+                int const pop_carry_over_time_range_id = cfg->getPaymentOptions().pop_carry_over_time_range_id;
+                QTime const carryOverTimeRangeFrom = cfg->TimeRange.find(pop_carry_over_time_range_id)->second.time_range_from;
+                QTime const carryOverTimeRangeTo = cfg->TimeRange.find(pop_carry_over_time_range_id)->second.time_range_to;
 
-                                int const timeStep = std::ceil(m_start.secsTo(carryOver) / 60.0);
-                                if (timeStep < duration.pun_duration_min || timeStep > duration.pun_duration_max) {
-                                    qCritical()
-                                        << QString("ERROR timeStep (%1) < durationMin (%2) || timeStep (%3)) > durationMax (%4)")
-                                            .arg(timeStep).arg(duration.pun_duration_min)
-                                            .arg(timeStep).arg(duration.pun_duration_max);
-                                    break;
+                if (carryOverTimeRangeFrom.secsTo(carryOverTimeRangeTo) <= 60) { // carry over time point, usually 00:00:00
+                    if (carryOverTimeRangeFrom == QTime(0, 0, 0)) {
+                        for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr) {
+                            int const durationId = itr->second.pra_payment_unit_id;
+                            auto search = cfg->Duration.find(durationId);
+                            if (search != cfg->Duration.end()) {
+                                ATBDuration duration = search->second;
+                                if (durationId == 1) {
+                                    QDateTime carryOver = start;
+                                    carryOver = carryOver.addDays(1);
+                                    carryOver.setTime(QTime(0, 0, 0));
+
+                                    int const timeStep = std::ceil(start.secsTo(carryOver) / 60.0);
+                                    if (timeStep < duration.pun_duration_min || timeStep > duration.pun_duration_max) {
+                                        qCritical()
+                                            << QString("ERROR timeStep (%1) < durationMin (%2) || timeStep (%3)) > durationMax (%4)")
+                                                .arg(timeStep).arg(duration.pun_duration_min)
+                                                .arg(timeStep).arg(duration.pun_duration_max);
+                                        break;
+                                    }
+                                    qCritical() << "configured minimal parking time:" << cfg->getPaymentOptions().pop_min_time;
+
+                                    // set dynamic minimal parking time
+                                    cfg->getPaymentOptions().pop_min_time = timeStep;
+
+                                    qCritical() << "  computed minimal parking time:" << cfg->getPaymentOptions().pop_min_time;
+
+                                    duration.pun_duration = timeStep;
+                                    timeStepCompensation = duration.pun_duration_max - duration.pun_duration;
+                                    timeSteps << duration.pun_duration;
+                                } else {
+                                    duration.pun_duration = duration.pun_duration_max - timeStepCompensation;
+                                    timeSteps << duration.pun_duration;;
                                 }
-                                duration.pun_duration = timeStep;
-                                m_timeStepCompensation = duration.pun_duration_max - duration.pun_duration;
-                                timeSteps << duration.pun_duration;
-                            } else {
-                                duration.pun_duration = duration.pun_duration_max - m_timeStepCompensation;
-                                timeSteps << duration.pun_duration;;
+
+                                cfg->Duration.erase(search);
+                                cfg->Duration.insert(pair<int, ATBDuration>(duration.pun_id, duration));
+
+                            } else { // if (search != cfg->Duration.end()) {
+                               // TODO
                             }
-
-                            cfg->Duration.erase(search);
-                            cfg->Duration.insert(pair<int, ATBDuration>(duration.pun_id, duration));
-
-                        } else { // if (search != cfg->Duration.end()) {
-                           // TODO
                         }
+                    } else { // if (carryOverTimeRangeFrom == QTime(0, 0, 0)) {
+                        // TODO
                     }
-                } else { // if (carryOverTimeRangeFrom == QTime(0, 0, 0)) {
+                } else { // if (carryOverTimeRangeFrom == carryOverTimeRangeTo) {
                     // TODO
                 }
-            } else { // if (carryOverTimeRangeFrom == carryOverTimeRangeTo) {
+            } else { // if (pop_carry_over) {
                 // TODO
             }
-        } else { // if (pop_carry_over) {
-            // TODO
-        }
-    } else {
-        for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr)
-        {
-            int const durationId = itr->second.pra_payment_unit_id;
-            int const durationUnit = cfg->Duration.find(durationId)->second.pun_duration;
-            timeSteps << durationUnit;
+        } else {
+            for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr)
+            {
+                int const durationId = itr->second.pra_payment_unit_id;
+                int const durationUnit = cfg->Duration.find(durationId)->second.pun_duration;
+                timeSteps << durationUnit;
+            }
         }
     }