diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java
index 92c0201ca..87524d7f2 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java
@@ -109,6 +109,8 @@ public interface IOrderElementDAO extends IIntegrationEntityDAO<OrderElement> {
 
     EffortDuration calculateMinWorkedHours(final List<OrderElement> list);
 
+    boolean isAlreadyInUse(OrderElement orderElement);
+
     boolean isAlreadyInUseThisOrAnyOfItsChildren(OrderElement orderElement);
 
     /**
@@ -130,6 +132,8 @@ public interface IOrderElementDAO extends IIntegrationEntityDAO<OrderElement> {
 
     boolean hasImputedExpenseSheet(Long id) throws InstanceNotFoundException;
 
+    boolean hasImputedExpenseSheetThisOrAnyOfItsChildren(Long id) throws InstanceNotFoundException;
+
     OrderElement findByExternalCode(String code) throws InstanceNotFoundException;
 
     public List<OrderElement> findByLabelsAndCriteria(Set<Label> labels,
diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java
index 50d44cb33..fe30ef96f 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java
@@ -421,7 +421,8 @@ public class OrderElementDAO extends IntegrationEntityDAO<OrderElement>
         return min;
     }
 
-    private boolean isAlreadyInUse(OrderElement orderElement) {
+    @Override
+    public boolean isAlreadyInUse(OrderElement orderElement) {
         if (orderElement.isNewObject()) {
             return false;
         }
@@ -518,7 +519,14 @@ public class OrderElementDAO extends IntegrationEntityDAO<OrderElement>
     }
 
     @Override
-    public boolean hasImputedExpenseSheet(Long id) throws InstanceNotFoundException {
+    public boolean hasImputedExpenseSheet(Long id)
+            throws InstanceNotFoundException {
+        OrderElement orderElement = find(id);
+        return (!expenseSheetLineDAO.findByOrderElement(orderElement).isEmpty());
+    }
+
+    @Override
+    public boolean hasImputedExpenseSheetThisOrAnyOfItsChildren(Long id) throws InstanceNotFoundException {
         OrderElement orderElement = find(id);
         return (!expenseSheetLineDAO.findByOrderElementAndChildren(orderElement).isEmpty());
     }
diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/orders/IOrderModel.java b/libreplan-webapp/src/main/java/org/libreplan/web/orders/IOrderModel.java
index 91a998699..b4261dbde 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/orders/IOrderModel.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/orders/IOrderModel.java
@@ -133,7 +133,7 @@ public interface IOrderModel extends IIntegrationEntityModel {
 
     PlanningState getPlanningState();
 
-    boolean hasImputedExpenseSheets(OrderElement order);
+    boolean hasImputedExpenseSheetsThisOrAnyOfItsChildren(OrderElement order);
 
     void removeAskedEndDate(EndDateCommunication endDate);
 
@@ -145,4 +145,7 @@ public interface IOrderModel extends IIntegrationEntityModel {
 
     boolean isAnyTaskWithConstraint(PositionConstraintType type);
 
+    boolean isOnlyChildAndParentAlreadyInUseByHoursOrExpenses(
+            OrderElement orderElement);
+
 }
diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderCRUDController.java b/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderCRUDController.java
index fbfa57a13..b49bea2c6 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderCRUDController.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderCRUDController.java
@@ -843,7 +843,7 @@ public class OrderCRUDController extends GenericForwardComposer {
     }
 
     private void remove(Order order) {
-        boolean hasImputedExpenseSheets = orderModel.hasImputedExpenseSheets(order);
+        boolean hasImputedExpenseSheets = orderModel.hasImputedExpenseSheetsThisOrAnyOfItsChildren(order);
         if (hasImputedExpenseSheets) {
             messagesForUser
                     .showMessage(
diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderElementTreeController.java b/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderElementTreeController.java
index f4d1d7f8e..79c2829c5 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderElementTreeController.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderElementTreeController.java
@@ -702,7 +702,8 @@ public class OrderElementTreeController extends TreeController<OrderElement> {
 
     @Override
     public void remove(OrderElement element) {
-        boolean hasImputedExpenseSheets = orderModel.hasImputedExpenseSheets(element);
+        boolean hasImputedExpenseSheets = orderModel
+                .hasImputedExpenseSheetsThisOrAnyOfItsChildren(element);
         if (hasImputedExpenseSheets) {
             messagesForUser
                     .showMessage(
@@ -719,10 +720,22 @@ public class OrderElementTreeController extends TreeController<OrderElement> {
                             Level.ERROR,
                             _("You cannot remove the task \"{0}\" because it has work reported on it or any of its children",
                                     element.getName()));
-        } else {
-            super.remove(element);
-            getRenderer().removeCodeTextbox(element);
+            return;
         }
+
+        boolean onlyChildAndParentAlreadyInUseByHoursOrExpenses = orderModel
+                .isOnlyChildAndParentAlreadyInUseByHoursOrExpenses(element);
+        if (onlyChildAndParentAlreadyInUseByHoursOrExpenses) {
+            messagesForUser
+                    .showMessage(
+                            Level.ERROR,
+                            _("You cannot remove the task \"{0}\" because it is the only child of its parent and its parent has tracked time or imputed expenses",
+                                    element.getName()));
+            return;
+        }
+
+        super.remove(element);
+        getRenderer().removeCodeTextbox(element);
     }
 
     @Override
diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderModel.java b/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderModel.java
index d32f21864..965695647 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderModel.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/orders/OrderModel.java
@@ -869,12 +869,12 @@ public class OrderModel extends IntegrationEntityModel implements IOrderModel {
 
     @Override
     @Transactional(readOnly = true)
-    public boolean hasImputedExpenseSheets(OrderElement order) {
+    public boolean hasImputedExpenseSheetsThisOrAnyOfItsChildren(OrderElement order) {
         if (order.isNewObject()) {
             return false;
         }
         try {
-            return orderElementDAO.hasImputedExpenseSheet(order.getId());
+            return orderElementDAO.hasImputedExpenseSheetThisOrAnyOfItsChildren(order.getId());
         } catch (InstanceNotFoundException e) {
             throw new RuntimeException(e);
         }
@@ -931,4 +931,24 @@ public class OrderModel extends IntegrationEntityModel implements IOrderModel {
         return planningState.getRootTask().isAnyTaskWithConstraint(type);
     }
 
+    @Override
+    @Transactional(readOnly = true)
+    public boolean isOnlyChildAndParentAlreadyInUseByHoursOrExpenses(
+            OrderElement orderElement) {
+        try {
+            OrderLineGroup parent = orderElement.getParent();
+            if (!parent.isOrder() && parent.getChildren().size() == 1) {
+                if (orderElementDAO.isAlreadyInUse(parent)) {
+                    return true;
+                }
+                if (orderElementDAO.hasImputedExpenseSheet(parent.getId())) {
+                    return true;
+                }
+            }
+            return false;
+        } catch (InstanceNotFoundException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
 }
diff --git a/libreplan-webapp/src/main/java/org/libreplan/ws/orders/impl/OrderElementServiceREST.java b/libreplan-webapp/src/main/java/org/libreplan/ws/orders/impl/OrderElementServiceREST.java
index 5c3c24c6a..a2326e108 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/ws/orders/impl/OrderElementServiceREST.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/ws/orders/impl/OrderElementServiceREST.java
@@ -169,22 +169,37 @@ public class OrderElementServiceREST extends
     }
 
     private String checkRemovalValidation(OrderElement orderElement) {
-        if (orderElementDAO.isAlreadyInUseThisOrAnyOfItsChildren(orderElement)) {
-            return "You cannot remove the order element '"
-                    + orderElement.getName()
-                    + "' because it or any of its children have tracked time in some work report";
-        }
         try {
-            if (orderElementDAO.hasImputedExpenseSheet(orderElement.getId())) {
+            if (orderElementDAO
+                    .isAlreadyInUseThisOrAnyOfItsChildren(orderElement)) {
                 return "You cannot remove the order element '"
                         + orderElement.getName()
-                        + "' because it or any of its children have tracked expenses in some expense sheet";
+                        + "' because it or any of its children have tracked time in some work report";
             }
+            if (orderElementDAO.hasImputedExpenseSheetThisOrAnyOfItsChildren(orderElement.getId())) {
+                return "You cannot remove the order element '"
+                        + orderElement.getName()
+                        + "' because it or any of its children have tracked expenses in some expenses sheet";
+            }
+
+            OrderLineGroup parent = orderElement.getParent();
+            if (!parent.isOrder() && parent.getChildren().size() == 1) {
+                if (orderElementDAO.isAlreadyInUse(parent)) {
+                    return "You cannot remove the order element '"
+                            + orderElement.getName()
+                            + "' because it is the only child of its parent and its parent has tracked time in some work report";
+                }
+                if (orderElementDAO.hasImputedExpenseSheet(parent.getId())) {
+                    return "You cannot remove the order element '"
+                            + orderElement.getName()
+                            + "' because it is the only child of its parent and its parent has tracked expenses in some expenses sheet";
+                }
+            }
+
+            return null;
         } catch (InstanceNotFoundException e) {
             throw new RuntimeException(e);
         }
-
-        return null;
     }
 
     private OrderElement findOrderElement(OrderElement orderElement, Long id) {