diff --git a/library/include/mobilisis/calculator_functions.h b/library/include/mobilisis/calculator_functions.h
index bdf2f3f..413429b 100644
--- a/library/include/mobilisis/calculator_functions.h
+++ b/library/include/mobilisis/calculator_functions.h
@@ -32,18 +32,20 @@ public:
     // Daily ticket
     QDateTime GetDailyTicketDuration(Configuration* cfg, const QDateTime start_datetime, uint8_t payment_option, bool carry_over);
 
+    //
+    // helper function to find time steps for a tariff with PaymentMethod::Steps
+    // (e.g. Schoenau/Koenigsee)
+    //
+    QList<int> GetTimeSteps(Configuration *cfg) const;
 
 private:
     // Introduced for PaymentMethod::Steps (e.g. Schoenau)
     // For tariff of following structure: only steps, no special days, nonstop.
-    uint32_t GetCostFromDuration(Configuration const* cfg, QDateTime const &start, quint64 durationMinutes, uint8_t paymentMethod = PaymentMethod::Steps);
-    uint32_t GetCostFromDuration(Configuration const* cfg, QDateTime const &start, QDateTime const &end, uint8_t paymentMethod = PaymentMethod::Steps);
+    uint32_t GetCostFromDuration(Configuration *cfg, QDateTime const &start, quint64 durationMinutes) const;
+    uint32_t GetCostFromDuration(Configuration *cfg, QDateTime const &start, QDateTime const &end) const;
 
 
     //
-    // helper functions for PaymentMethod::Steps
-    //
-    QList<int> GetTimeSteps(Configuration const *cfg, int paymentMethod);
-    //
-    uint32_t GetPriceForTimeStep(Configuration const *cfg, uint8_t paymentMethod, int timeStep);
+    uint32_t GetPriceForTimeStep(Configuration *cfg, int timeStep) const;
+    uint32_t GetDurationForPrice(Configuration *cfg, int price) const;
 };
diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index 060b049..9442587 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -118,6 +118,15 @@ std::string Calculator::GetDurationFromCost(Configuration* cfg,
                                             bool nextDay,
                                             bool prepaid)
 {
+    // use tariff with structure as for instance Schnau, Koenigsee:
+    // without given YearPeriod, SpecialDays and SpecialDaysWorktime
+    if (cfg->YearPeriod.size() == 0
+        && cfg->SpecialDays.size() == 0
+        && cfg->SpecialDaysWorktime.size() == 0)
+    {
+        return QString().setNum(GetDurationForPrice(cfg, price)).toStdString();
+    }
+
     // Get input date
     QDateTime inputDate = QDateTime::fromString(start_datetime,Qt::ISODate);
 
@@ -341,30 +350,28 @@ std::string Calculator::GetDurationFromCost(Configuration* cfg,
 /// <inheritdoc/>
 ///
 
-uint32_t Calculator::GetCostFromDuration(Configuration const* cfg,
+uint32_t Calculator::GetCostFromDuration(Configuration *cfg,
                                          QDateTime const &start,
-                                         quint64 timeStepInMinutes,
-                                         uint8_t paymentMethod) {
+                                         quint64 timeStepInMinutes) const {
     // for instance, a tariff as used in Schoenau, Koenigssee: only steps, no
     // special days, nonstop.
-    if (paymentMethod == PaymentMethod::Steps
+    if (cfg->YearPeriod.size() == 0
      && cfg->SpecialDays.size() == 0
      && cfg->SpecialDaysWorktime.size() == 0) {
         QDateTime const end = start.addSecs(timeStepInMinutes*60);
-        return GetCostFromDuration(cfg, start, end, paymentMethod);
+        return GetCostFromDuration(cfg, start, end);
     }
     return 0;
 }
 
-uint32_t Calculator::GetCostFromDuration(Configuration const* cfg,
+uint32_t Calculator::GetCostFromDuration(Configuration * cfg,
                                          QDateTime const &start,
-                                         QDateTime const &end,
-                                         uint8_t paymentMethod) {
-    if (paymentMethod == PaymentMethod::Steps
+                                         QDateTime const &end) const {
+    if (cfg->YearPeriod.size() == 0
      && cfg->SpecialDays.size() == 0
      && cfg->SpecialDaysWorktime.size() == 0) {
         int const timeStepInMinutes = start.secsTo(end) / 60;
-        return GetPriceForTimeStep(cfg, paymentMethod, timeStepInMinutes);
+        return GetPriceForTimeStep(cfg, timeStepInMinutes);
     }
     return 0;
 }
@@ -377,12 +384,12 @@ uint32_t Calculator::GetCostFromDuration(Configuration const* cfg,
 /// <inheritdoc/>
 double Calculator::GetCostFromDuration(Configuration* cfg, uint8_t payment_option, const QDateTime start_datetime, QDateTime & end_datetime,  double durationMin, bool nextDay, bool prepaid)
 {
-    // condition for 'PaymentMethod::Steps' (e.g. 332/Schoenau):
-    if (cfg->SpecialDays.size() == 0
+    if (cfg->YearPeriod.size() == 0
+        && cfg->SpecialDays.size() == 0
         && cfg->SpecialDaysWorktime.size() == 0)
     {
         end_datetime = start_datetime.addSecs(durationMin*60);
-        return GetCostFromDuration(cfg, start_datetime, end_datetime, PaymentMethod::Steps);
+        return GetCostFromDuration(cfg, start_datetime, end_datetime);
     }
 
     // Get input date
@@ -588,10 +595,10 @@ double Calculator::GetCostFromDuration(Configuration* cfg, uint8_t payment_optio
 
 
 
-QList<int> Calculator::GetTimeSteps(Configuration const *cfg, int paymentOption) {
+QList<int> Calculator::GetTimeSteps(Configuration *cfg) const {
     QList<int> timeSteps;
 
-    int const pop_id = cfg->PaymentOption.find(paymentOption)->second.pop_id;
+    int const pop_id = cfg->getPaymentOptions().pop_id;
 
     for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr)
     {
@@ -603,9 +610,9 @@ QList<int> Calculator::GetTimeSteps(Configuration const *cfg, int paymentOption)
     return timeSteps;
 }
 
-uint32_t Calculator::GetPriceForTimeStep(Configuration const *cfg, uint8_t paymentOption, int timeStep) {
+uint32_t Calculator::GetPriceForTimeStep(Configuration *cfg, int timeStep) const {
 
-    int const pop_id = cfg->PaymentOption.find(paymentOption)->second.pop_id;
+    int const pop_id = cfg->getPaymentOptions().pop_id;
 
     for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr)
     {
@@ -616,7 +623,25 @@ uint32_t Calculator::GetPriceForTimeStep(Configuration const *cfg, uint8_t payme
 
         int const pun_duration = cfg->Duration.find(payment_unit_id)->second.pun_duration;
         if (timeStep == pun_duration) {
-                return (uint32_t)(itr->second.pra_price);
+            return (uint32_t)(itr->second.pra_price);
+        }
+    }
+
+    return 0;
+}
+
+uint32_t Calculator::GetDurationForPrice(Configuration *cfg, int price) const {
+    int const pop_id = cfg->getPaymentOptions().pop_id;
+
+    for (auto[itr, rangeEnd] = cfg->PaymentRate.equal_range(pop_id); itr != rangeEnd; ++itr)
+    {
+        int const payment_unit_id = itr->second.pra_payment_unit_id;
+        int const pra_price = cfg->PaymentRate.find(payment_unit_id)->second.pra_price;
+
+        if (price == pra_price) {
+            int const durationId = itr->second.pra_payment_unit_id;
+            int const durationUnit = cfg->Duration.find(durationId)->second.pun_duration;
+            return durationUnit;
         }
     }