diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index d944ec4..1725d9f 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -312,29 +312,50 @@ std::optional<ATBTariffOutOfService> getOutOfService(Configuration const *cfg, Q
     std::optional<ATBTariffOutOfService> value = std::nullopt;
 
     int weekDay = dt.date().dayOfWeek();
+    // qCritical() << __func__ << ":" << __LINE__ << dt.toString(Qt::ISODate) << weekDay;
+
     ATBTime inputTime(dt.time());
     QDate date;
 
     auto const &outOfServiceRange = cfg->TariffOutOfServices.equal_range(weekDay);
+
+    QDate d; // check if a special date is configured in tariff-file for this day
     for (auto i = outOfServiceRange.first; i != outOfServiceRange.second; ++i) {
         ATBTariffOutOfService const &outOfService = i->second;
-        TimeRange const &outOfServiceTimeRange = outOfService.m_range;
-        if (outOfService.m_date == dt.date()) {
-            date = dt.date();
-            if (inputTime >= outOfServiceTimeRange.m_start && inputTime < outOfServiceTimeRange.m_end) {
-                value = value.value_or(i->second);
-                return value;
-            }
+        if (!outOfService.m_date.isNull() && outOfService.m_date.isValid() && outOfService.m_date == dt.date()) {
+            d = dt.date();
+            // qCritical() << __func__ << ":" << __LINE__ << "found special day" << d.toString(Qt::ISODate);
+            break;
         }
     }
 
-    if (date.isNull() || !date.isValid()) {
+    if (!d.isNull() && d.isValid()) {
         for (auto i = outOfServiceRange.first; i != outOfServiceRange.second; ++i) {
             ATBTariffOutOfService const &outOfService = i->second;
-            TimeRange const &outOfServiceTimeRange = outOfService.m_range;
-            if (inputTime >= outOfServiceTimeRange.m_start && inputTime < outOfServiceTimeRange.m_end) {
-                value = value.value_or(i->second);
-                return value;
+
+            if (!outOfService.m_date.isNull() && outOfService.m_date.isValid() && outOfService.m_date == d) {
+                TimeRange const &outOfServiceTimeRange = outOfService.m_range;
+                if (inputTime >= outOfServiceTimeRange.m_start && inputTime < outOfServiceTimeRange.m_end) {
+                    // qCritical() << __func__ << ":" << __LINE__ << outOfServiceTimeRange.m_start.toString(Qt::ISODate);
+                    // qCritical() << __func__ << ":" << __LINE__ << outOfServiceTimeRange.m_end.toString(Qt::ISODate);
+                    value = value.value_or(outOfService);
+                    break;
+                }
+            }
+        }
+    } else {
+        // qCritical() << __func__ << ":" << __LINE__ << "no special day" << dt.date().toString(Qt::ISODate);
+        for (auto i = outOfServiceRange.first; i != outOfServiceRange.second; ++i) {
+            ATBTariffOutOfService const &outOfService = i->second;
+            if (outOfService.m_date.isNull() || !outOfService.m_date.isValid()) {
+                // qCritical() << __func__ << ":" << __LINE__ << "default";
+                TimeRange const &outOfServiceTimeRange = outOfService.m_range;
+                if (inputTime >= outOfServiceTimeRange.m_start && inputTime < outOfServiceTimeRange.m_end) {
+                    // qCritical() << __func__ << ":" << __LINE__ << outOfServiceTimeRange.m_start.toString(Qt::ISODate);
+                    // qCritical() << __func__ << ":" << __LINE__ << outOfServiceTimeRange.m_end.toString(Qt::ISODate);
+                    value = value.value_or(outOfService);
+                    break;
+                }
             }
         }
     }