diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index 24b87ba..5b1a1c7 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -320,17 +320,17 @@ std::string Calculator::GetDurationFromCost(Configuration* cfg,
 
                             lastCurrent = current;
                             current.setTime(to);
-                            int const minsLeft = lastCurrent.secsTo(current) / 60;
+                            int const minsUsed = lastCurrent.secsTo(current) / 60;
 
                             // mod duration: possibly discard some minutes in
                             // the next time-range
-                            minsToCarryOver = (durationMinutes - minsLeft) % duration;
+                            minsToCarryOver = (durationMinutes - minsUsed) % duration;
 
-                            durationMinutes -= minsLeft;
-                            durationMinutesNetto += minsLeft;
-                            durationMinutesBrutto += minsLeft;
+                            durationMinutes -= minsUsed;
+                            durationMinutesNetto += minsUsed;
+                            durationMinutesBrutto += minsUsed;
 
-                            if (minsLeft > 0) {
+                            if (minsUsed > 0) {
                                 for(const auto &x: cfg->PaymentRate) {
                                     ATBPaymentRate const rate = x.second;
                                     if (rate.pra_payment_unit_id == timeRange.time_range_payment_type_id) {
@@ -569,6 +569,7 @@ double Calculator::GetCostFromDuration(Configuration* cfg,
         if (carryOverNotSet) {
             int range = 0;
             int minsToCarryOver = 0; // from one work-time to the other on the same day
+            int minsUsed = 0;
             QDateTime lastCurrent = QDateTime();
 
             auto timeRangeIt = cfg->TimeRange.cbegin();
@@ -609,18 +610,23 @@ double Calculator::GetCostFromDuration(Configuration* cfg,
                         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) {
+                        if (minsUsed > 0) {
+                            duration -= minsUsed;
+                            minsUsed = 0;
+                        }
 
-                            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 {
+                        if (current.addSecs(duration * 60).time() <= to) {
+                            if (minsToCarryOver > 0) {  // the price for this time range
+                                                        // has been is paid already
+                                durationMinutes -= duration;
+                                durationMinutesNetto += duration;
+                                durationMinutesBrutto += duration;
+                                current = current.addSecs(duration*60);
+                                minsToCarryOver = 0;
+                            } else {
+                                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;
 
                                         durationMinutes -= duration;
@@ -628,8 +634,8 @@ double Calculator::GetCostFromDuration(Configuration* cfg,
                                         durationMinutesBrutto += duration;
 
                                         current = current.addSecs(duration * 60);
+                                        break;
                                     }
-                                    break;
                                 }
                             }
 
@@ -644,17 +650,19 @@ double Calculator::GetCostFromDuration(Configuration* cfg,
 
                             lastCurrent = current;
                             current.setTime(to);
-                            int const minsLeft = lastCurrent.secsTo(current) / 60;
+                            minsUsed = lastCurrent.secsTo(current) / 60;
 
                             // mod duration: possibly discard some minutes in
                             // the next time-range
-                            minsToCarryOver = (durationMinutes - minsLeft) % duration;
+                            if (durationMinutes >= minsUsed) {
+                                minsToCarryOver = durationMinutes - minsUsed;
+                            }
 
-                            durationMinutes -= minsLeft;
-                            durationMinutesNetto += minsLeft;
-                            durationMinutesBrutto += minsLeft;
+                            durationMinutes -= minsUsed;
+                            durationMinutesNetto += minsUsed;
+                            durationMinutesBrutto += minsUsed;
 
-                            if (minsLeft > 0) {
+                            if (minsUsed > 0) {
                                 for(const auto &x: cfg->PaymentRate) {
                                     ATBPaymentRate const rate = x.second;
                                     if (rate.pra_payment_unit_id == timeRange.time_range_payment_type_id) {
@@ -663,7 +671,6 @@ double Calculator::GetCostFromDuration(Configuration* cfg,
                                     }
                                 }
                             }
-
                             break;
                         }
                     }