diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index 986dadf..1b7cb56 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -255,7 +255,7 @@ CalcState Calculator::isParkingAllowed(Configuration const *cfg, QDateTime const
 /// <inheritdoc/>
 double Calculator::GetCostFromDuration(Configuration* cfg,
                                        uint8_t payment_option,
-                                       const QDateTime start_datetime,
+                                       QDateTime &start_datetime,
                                        QDateTime &end_datetime,
                                        int durationMinutes,
                                        bool nextDay,
@@ -286,6 +286,179 @@ double Calculator::GetCostFromDuration(Configuration* cfg,
                 return 0;
             }
         }
+    } else
+    if (paymentMethodId == PaymentMethod::Progressive) {
+        // started with Neuhauser, Kirchdorf: merge into main algo. later
+        // for now try out some ideas
+
+        static const bool carryOverNotSet = Utilities::isCarryOverNotSet(cfg, paymentMethodId);
+        static const uint minParkingPrice = Utilities::getMinimalParkingPrice(cfg, paymentMethodId);
+
+        Q_ASSERT_X(carryOverNotSet, __func__, "CARRYOVER SET (FOR KIRCHDORF)");
+        Q_ASSERT_X(prepaid, __func__, "PREPAID NOT SET (FOR KIRCHDORF)");
+
+        QDateTime start = start_datetime;
+
+        int weekdayId = -1;
+        int weekdayIdLast = -1;
+        int timeRanges = 0;
+        int durationMinutesBrutto = 0;
+
+        QDateTime current = start;
+
+        int days = 7;
+        while (--days > 0) {
+            weekdayId = current.date().dayOfWeek();
+            weekdayIdLast = weekdayId; // TODO: some end condition in json-file
+
+            while ((timeRanges = cfg->WeekDaysWorktime.count(weekdayId)) == 0) {
+                current = current.addDays(1);
+                weekdayId = current.date().dayOfWeek();
+                if (weekdayId == weekdayIdLast) {
+                    qCritical() << "ERROR: NO VALID WORKDAY-TIMES DEFINED";
+                    return 0;
+                }
+            }
+
+            using WTIterator = std::multimap<int, ATBWeekDaysWorktime>::const_iterator;
+            std::pair<WTIterator, WTIterator> p = cfg->WeekDaysWorktime.equal_range(weekdayId);
+
+            QTime to = QTime(0, 0, 0);
+            for (WTIterator itr = p.first; itr != p.second; ++itr) {
+                QTime const &t = Utilities::WeekDaysWorkTimeUntil(itr);
+
+                if (to < t) {
+                    to = t;
+                }
+            }
+
+
+            if (current.time() >= to) {
+                QDateTime const dt = start;
+                start = start.addDays(1);
+                start.setTime(QTime(0, 0, 0));
+
+                durationMinutesBrutto += dt.secsTo(start) / 60;
+                current = start;
+            } else {
+                break;
+            }
+        }
+
+        int durationMinutesNetto = 0;
+        uint price = 0;
+
+        if (carryOverNotSet) {
+            int range = 0;
+            int minsToCarryOver = 0; // from one work-time to the other on the same day
+            QDateTime lastCurrent = QDateTime();
+
+            auto timeRangeIt = cfg->TimeRange.cbegin();
+            for (; timeRangeIt != cfg->TimeRange.cend(); ++timeRangeIt) {
+                using WTIterator = std::multimap<int, ATBWeekDaysWorktime>::const_iterator;
+                std::pair<WTIterator, WTIterator> p = cfg->WeekDaysWorktime.equal_range(weekdayId);
+
+                for (WTIterator itr = p.first; itr != p.second; ++itr) {
+                    ++range;
+
+                    QTime const &from = Utilities::WeekDaysWorkTimeFrom(itr);
+                    QTime const &to = Utilities::WeekDaysWorkTimeUntil(itr);
+
+                    Q_ASSERT_X(from < to, __func__, "MISCONFIGURED WORK-TIMES");
+
+
+                    if (current.time() >= to) {
+                        continue; // try to use next available work-time
+                    } else
+                    if (current.time() <= from) {
+                        if (prepaid) {
+                            lastCurrent = current;
+                            current.setTime(from); // move current forward (range==1),
+                                                   // as prepaid is set
+                            uint const minutesMoved = lastCurrent.secsTo(current) / 60;
+                            durationMinutesBrutto += minutesMoved;
+
+                            if (range == 1) {
+                                start_datetime = current;
+                            }
+                        }
+                    }
+
+                    while (timeRangeIt != cfg->TimeRange.cend()) {
+                        ATBTimeRange timeRange = timeRangeIt->second;
+
+                        timeRange.computeQTimes(current.time());
+
+                        int duration = timeRange.time_range_to_in_minutes_from_start -
+                                       timeRange.time_range_from_in_minutes_from_start;
+
+                        if (current.addSecs(duration * 60).time() <= to) {
+
+                            for(const auto &x: cfg->PaymentRate) {
+                                ATBPaymentRate const rate = x.second;
+                                if (rate.pra_payment_unit_id == timeRange.time_range_payment_type_id) {
+                                    if (minsToCarryOver > 0) {
+                                        durationMinutes -= minsToCarryOver;
+                                        durationMinutesNetto += minsToCarryOver;
+                                        durationMinutesBrutto += minsToCarryOver;
+                                        current = current.addSecs(minsToCarryOver*60);
+                                        minsToCarryOver = 0;
+                                    } else {
+                                        price += (uint)rate.pra_price;
+
+                                        durationMinutes -= duration;
+                                        durationMinutesNetto += duration;
+                                        durationMinutesBrutto += duration;
+
+                                        current = current.addSecs(duration * 60);
+                                    }
+                                    break;
+                                }
+                            }
+
+                            if (durationMinutes <= 0) {
+                                end_datetime = current;
+                                return price;
+                            }
+
+                            ++timeRangeIt;
+
+                        } else {
+
+                            lastCurrent = current;
+                            current.setTime(to);
+                            int const minsLeft = lastCurrent.secsTo(current) / 60;
+
+                            // mod duration: possibly discard some minutes in
+                            // the next time-range
+                            minsToCarryOver = (durationMinutes - minsLeft) % duration;
+
+                            durationMinutes -= minsLeft;
+                            durationMinutesNetto += minsLeft;
+                            durationMinutesBrutto += minsLeft;
+
+                            if (minsLeft > 0) {
+                                for(const auto &x: cfg->PaymentRate) {
+                                    ATBPaymentRate const rate = x.second;
+                                    if (rate.pra_payment_unit_id == timeRange.time_range_payment_type_id) {
+                                        price += (uint)rate.pra_price;
+                                        break;
+                                    }
+                                }
+                            }
+
+                            break;
+                        }
+                    }
+                }
+
+                end_datetime = start.addSecs(durationMinutesBrutto * 60);
+                return std::max(price, minParkingPrice);
+            }
+        }
+
+        end_datetime = QDateTime();
+        return 0;
     }
 
     QDateTime start = start_datetime;